Transformation of criminal proceedings in the context of digitalisation: admissibility of evidence and prospects for integrating blockchain technologies into law enforcement practice

1 Introduction

The advent of digital technologies has brought profound changes to multiple sectors, and criminal justice is no exception. Digital tools and platforms are reshaping investigations, prosecutions, and court proceedings, creating opportunities to streamline workflows, reduce procedural delays, and improve overall efficiency. Miró-Llinares and Aebi (2025) emphasise that digitalisation affects crime patterns indirectly by altering social routines, particularly among youth, who spend more time in digital spaces than public ones. This requires justice systems to adapt both operationally and structurally. The integration of electronic filing systems, case management platforms, and communication technologies facilitates timely information exchange and coordination across agencies. Digitalisation also demands interdisciplinary collaboration between legal authorities, law enforcement, and technology specialists. As criminal justice processes become more digitally mediated, understanding the societal, procedural, and technical implications is essential for effective system transformation. This technological shift lays the groundwork for further innovations, including blockchain-based solutions, while highlighting the need to balance efficiency with accountability and fairness.

Digitalisation provides substantial potential to make criminal proceedings more efficient and transparent. Jubaer (2025) demonstrates that e-courts and digital case management systems streamline administrative operations and minimise human error while ensuring timely access to procedural information. Ilchyshyn (2025) highlights that digital tools optimise administrative justice by providing consistent access to case files and improving procedural oversight. Mahmood et al. (2025) show that cybersecurity and AI integration protect the integrity of digital processes while enabling predictive crime detection. Automated systems and digital workflows facilitate inter-agency coordination, auditing, and monitoring of procedural compliance. They also reduce discrepancies in case handling across jurisdictions and improve the consistency of legal outcomes. By enhancing transparency, digitalisation enables both oversight authorities and the public to monitor case developments in real time. The combination of efficiency, auditability, and accountability contributes to stronger institutional legitimacy and public confidence. These improvements underscore the critical role of technology in modernising judicial administration while safeguarding procedural fairness.

Beyond efficiency, digitalisation significantly enhances access to justice by reducing geographic, logistical, and institutional barriers. Joshi et al. (2025) emphasise that electronic evidence and online submission platforms allow individuals and legal professionals to participate meaningfully in proceedings, regardless of physical location. Digital public records and virtual hearings also facilitate greater transparency, enabling oversight bodies to monitor case developments. Mahmood et al. (2025) highlight that AI and blockchain solutions ensure secure participation while maintaining the privacy and integrity of sensitive data. These tools reduce disparities for marginalised populations and enable broader engagement in judicial processes. Improved accessibility fosters public trust and promotes procedural inclusivity, allowing justice systems to operate more equitably. By enabling real-time monitoring and engagement, digitalisation empowers stakeholders to act with informed oversight. The integration of these technologies also provides opportunities for public education and awareness regarding procedural rights and responsibilities. Ultimately, accessibility complements efficiency and transparency, creating a more responsive and accountable justice system.

Despite these benefits, digitalisation introduces significant challenges concerning the collection, verification, and admissibility of digital evidence. Miller (2023) notes that rapidly evolving technologies make it difficult for prosecutors and investigators to interpret and present electronic data accurately. Iaiani et al. (2023) highlight that malicious interferences, analogous to cyberattacks in industrial control systems, can compromise the integrity and reliability of digital platforms used in criminal justice, creating vulnerabilities that threaten procedural consistency and data authenticity. Narasimhan and Kala (2024) emphasise the critical role of the Chain of Custody (CoC) in digital forensics, illustrating that meticulous documentation, secure storage, and controlled access at every stage of evidence handling are essential to maintaining credibility, supporting legal admissibility, and preventing evidence contamination. AI analytics, blockchain logs, and electronic communications similarly require rigorous oversight to ensure compliance with legal and procedural standards. Without these safeguards, the reliability of judicial outcomes and public confidence may be undermined. Addressing these challenges demands specialised training, cross-disciplinary collaboration, and adaptive regulatory frameworks. Continuous evaluation of technological innovations and procedural safeguards is necessary to maintain fairness, integrity, and accountability, ensuring that the opportunities of digital evidence are realised without compromising justice.

This review examines the transformation of criminal proceedings under digitalisation by analysing the admissibility of digital evidence and the prospects for integrating blockchain technologies into law enforcement practice. Its contribution lies in treating blockchain not as a stand-alone technological remedy but as a governed evidentiary verification layer embedded within legal procedure, forensic practice, institutional accountability and judicial interpretation. The review advances a blockchain-enabled evidentiary governance framework that connects evidence generation, chain-of-custody management, blockchain verification, legal admissibility, and judicial trust outcomes. It also separates established findings from pilot-stage evidence and future hypotheses, thereby clarifying where blockchain-based criminal justice reform is empirically supported and where it remains legally, technically or institutionally uncertain. This framing supports a balanced assessment of digital transformation, where efficiency, accessibility and transparency are evaluated alongside fairness, privacy, contestability, and due process.

2 Review methodology

2.1 Search strategy and eligibility criteria

The review followed a structured, multidisciplinary literature review design to improve transparency, reproducibility, and conceptual coherence. Searches were conducted across Scopus, Web of Science, ScienceDirect, SpringerLink, IEEE Xplore, Google Scholar, institutional repositories, official justice-sector resources, and selected legal databases. The search strategy combined terms related to criminal proceedings, criminal justice, law enforcement, digital evidence, electronic evidence, digital forensics, chain of custody, evidence admissibility, blockchain, distributed ledger technology, smart contracts, forensic logging, judicial digitalisation, e-courts, data protection and cross-border evidence. Boolean combinations were used to capture the intersection between legal admissibility, digital forensic reliability, and blockchain-enabled governance. The main time horizon covered literature published from 2015 to 2026, while older foundational legal, technical, and policy sources were retained where they remained necessary for interpreting evidentiary doctrine, identity governance, or blockchain architecture.

Sources were screened through title, abstract, and full-text review. Included materials addressed at least one of the following dimensions: digitalisation of criminal justice processes, digital evidence collection and preservation, forensic validation, legal admissibility, blockchain-based evidence management, smart contracts, privacy-preserving verification, jurisdictional conflicts, algorithmic accountability or law-enforcement implementation. Studies were excluded when they discussed blockchain in unrelated sectors without transferable evidentiary relevance, offered unsupported promotional claims, lacked sufficient methodological or doctrinal detail, or duplicated information already captured by higher-quality sources. During synthesis, each source was coded by jurisdictional context, evidence lifecycle stage, technology type, blockchain architecture, implementation maturity, legal relevance, governance requirements, risk profile, and justice-system implication. This coding enabled the review to differentiate established findings from emerging evidence and future hypotheses rather than presenting all blockchain applications as equally mature.

2.2 Analytical synthesis and conceptual framework

The synthesis used a thematic and conceptual approach. Thematic analysis grouped the literature into five recurring domains: digitalisation of criminal proceedings, digital evidence management, admissibility and procedural fairness, blockchain integration in law enforcement, and autonomous or algorithmic justice systems. Conceptual synthesis then examined how technical features such as hashing, timestamping, distributed consensus, permissioned access, smart contracts, and privacy-preserving computation interact with legal concepts such as authenticity, integrity, relevance, chain of custody, due process, equality of arms, and judicial trust. This approach allowed technical claims about blockchain to be evaluated through legal and institutional criteria rather than through technological capability alone.

The resulting conceptual framework treats digital evidence governance as a sequence of linked evidentiary events. Evidence is first generated by devices, platforms, transactions or investigative actions; it is then acquired, hashed, documented, preserved and analysed within a chain-of-custody environment. Blockchain contributes to the verification layer by recording cryptographic metadata, handling events, access permissions, and procedural milestones, while the evidentiary object itself is usually retained off-chain in secure forensic repositories. Legal admissibility depends on whether the blockchain record supports, rather than replaces, proof of authenticity, integrity, legality, relevance and contestability. Judicial trust emerges when courts, prosecutors, defence counsel and oversight bodies can interrogate both the underlying evidence and the technical governance of the ledger. The framework therefore connects digital evidence generation, chain-of-custody management, blockchain verification, legal admissibility and judicial trust outcomes within one socio-technical model.

3 Digitalisation of criminal proceedings

3.1 Adoption of digital tools in criminal justice

The adoption of digital tools within criminal justice systems marks one of the most consequential transformations in modern governance. However, as the literature reveals, this transformation is neither uniform nor unproblematic, and progress is shaped by technological capacity, socio-legal context, and institutional readiness. Comparative evidence from global, European and transnational e-justice studies shows that digital court systems can improve case processing, transparency and access to judicial services, but these gains remain uneven because technological infrastructure, institutional capacity, digital literacy and procedural safeguards differ substantially across jurisdictions, thereby challenging the assumption that digitisation alone produces a genuinely “smart” justice system (Maroz et al., 2023; Velicogna, 2007; Lupo and Bailey, 2014; Sourdin et al., 2020; Simmler et al., 2023). Across jurisdictions, the integration of electronic case management, digital filing, and virtual hearings has demonstrably improved the efficiency and accessibility of justice. Upegui Caro (2025) provides robust empirical data showing that electronic case management reduced case resolution times by 13% in adjudication and 11% in enforcement in Brazil’s labour courts. Similar successes in Kenya and Albania, where digital tracking and recording improved judicial accountability and transparency, affirm the established finding that digitalisation streamlines procedural management and enhances institutional visibility. This aligns with findings from Prayoga (2024) and Situmeang et al. (2024), who observe that digital forensics, AI-assisted evidence analysis, and big data applications significantly improve investigative precision and case processing. AI tools for pattern recognition and predictive policing, when used responsibly, have reduced manual errors and optimised resource allocation in several pilot jurisdictions. These results reinforce what may now be considered an established consensus: digital technologies, when properly implemented, enhance both administrative efficiency and public access to justice. Yet the same body of research cautions against techno-optimism. Gaffar (2024), drawing on Law and Society and Legal Realism frameworks, highlights a structural paradox: digitalisation can both democratise and stratify justice access. While high-income countries have achieved near-complete digital transformation [88% adoption of court digitalisation reforms (Upegui Caro, 2025)], low-income countries remain far behind at 17%, underscoring a digital divide that threatens procedural fairness.

Similarly, Laufs and Borrion (2022) found that despite technological enthusiasm in policing, implementation is hindered by a lack of interoperability, inadequate funding, and weak institutional coordination. Practitioners in London reported that technological innovation is often constrained by bureaucratic inertia and fragmented IT ecosystems. These findings reveal a critical bottleneck: digital adoption without institutional integration often produces fragmented justice systems rather than cohesive, data-driven networks.

Building on this critique, Simmler et al. (2023) argue that not every digital innovation is “smart” justice. They propose a normative framework that evaluates digital tools by efficiency, legality, equality, and transparency. Their analysis reveals that technologies promising automation, such as algorithmic sentencing and AI-driven risk assessments, may undermine fundamental legal principles if adopted without adequate oversight. Similarly, Situmeang et al. (2024) identify bias and opacity in AI decision systems as enduring risks to civil liberties and due process. This body of work converges on an essential insight: technological efficiency cannot substitute for procedural justice. Established findings confirm the operational gains of digital tools, but emerging hypotheses suggest that over-automation may erode human judgment and accountability, creating a new form of digital paternalism in law enforcement.

Borgesano et al. (2025) extend this discourse into the “Justice 5.0” paradigm, where the goal shifts from technological optimisation to human-centred AI integration. Their systematic review of 140 studies identifies three streams of AI innovation: predictive justice, human–machine collaboration, and robot judges. Empirical evidence supports the effectiveness of hybrid models where AI complements, rather than replaces, human adjudication. However, the feasibility of full automation, “robot judges”, remains largely hypothetical, with substantial ethical and legal reservations. The Justice 5.0 perspective offers a corrective to earlier techno-centric models: the value of digitalisation lies not merely in speed or automation, but in how it augments fairness, inclusivity, and human oversight. This is consistent with Gaffar's (2024) socio-legal approach, which emphasises balancing efficiency with the social function of law.

The comparative evidence underscores several lessons. First, contextual adaptation is key: technologies that succeed in high-resource settings may exacerbate inequalities elsewhere. Second, institutional interoperability and capacity-building are critical prerequisites; as Laufs and Borrion (2022) show, technical tools fail when not embedded in coherent governance frameworks. Third, ethical infrastructure, transparency, accountability, and bias mitigation must evolve alongside technical innovation. In synthesis, the adoption of digital tools in criminal justice has achieved procedural acceleration and improved access, but also revealed jurisdictional asymmetries, ethical vulnerabilities, and governance gaps. The shift towards Justice 5.0 thus represents a normative transition: from viewing digitalisation as a purely technical reform to understanding it as a socio-technical transformation requiring robust human, legal, and institutional safeguards (Figure 1).

The digital divide identified in the adoption data is therefore treated here as a governance challenge rather than as a purely technical lag. Because resource-limited jurisdictions cannot safely move from fragmented paper-based systems directly to advanced AI or blockchain-enabled justice platforms, the mitigation pathway is developed in Section 8.5 through a phased, resource-sensitive model of basic digital infrastructure, shared forensic capacity and sustained professional training (Organisation for Economic Co-operation and Development, 2024; Heeks, 2021).

3.2 Challenges in digital evidence management

The management of digital evidence constitutes one of the most complex and contested dimensions of digitalised criminal justice. Unlike physical evidence, digital artefacts are intangible, easily altered, and dependent on rapidly evolving infrastructures. Their admissibility depends not only on technical integrity but also on procedural legitimacy and judicial comprehension. The convergence of computer forensics, data science, and procedural law has exposed deep institutional and conceptual gaps that continue to challenge evidentiary reliability across jurisdictions. One of the most persistent problems concerns the preservation and authenticity of digital artefacts. Granja and Rafael (2017) highlighted that traditional models of evidence preservation, designed for static and physical media, are ill-suited for the dynamic nature of digital data. The continual obsolescence of file formats, hardware, and software undermines the capacity of judicial institutions to ensure long-term accessibility and evidentiary authenticity. Their work revealed that data migration strategies, although common in archival science, can inadvertently compromise the metadata needed to demonstrate provenance and chain of custody. The difficulty of preserving not only the data but also the context of its generation has led to proposals for integrated forensic-archival systems, yet implementation remains sporadic and unstandardised. These weaknesses illustrate the broader absence of a unified legal-forensic model capable of guaranteeing continuity between technical storage and legal admissibility.

The chain of custody represents another persistent source of vulnerability. Nath et al. (2024) compared three prevailing paradigms: traditional paper documentation, system-based digital logs, and blockchain-oriented infrastructures. Each framework embodies a trade-off between familiarity, efficiency, and integrity. Paper records retain legal legitimacy but are unfit for managing high-volume or multi-jurisdictional digital evidence. System-based approaches increase automation but remain vulnerable to insider manipulation and retrospective editing. Blockchain, by contrast, introduces immutability and decentralisation, making unauthorised modification more readily detectable under appropriate governance eliminating tampering, yet it raises new questions about scalability, privacy, and legal recognition. Most jurisdictions lack procedural rules addressing how blockchain-stored data should be validated, interpreted, or contested in court. The technology, therefore, exists in a regulatory vacuum, where its technical promise is unmatched by institutional or normative maturity. The unresolved question is not whether blockchain enhances evidentiary security, but whether judicial systems can evolve sufficiently to accommodate its epistemic logic.

Institutional capacity and professional competence also play a decisive role. Miller (2023) demonstrated that discrepancies between the technical expertise of forensic investigators and the legal understanding of prosecutors lead to significant distortions in evidentiary evaluation. Many legal professionals remain unfamiliar with the operational and interpretive dimensions of digital forensics, resulting in over-reliance on expert witnesses or the mischaracterisation of digital artefacts in court. Such gaps are symptomatic of broader structural inertia in legal education and judicial training, where the law’s conceptual tools have not evolved at the same pace as technological change. These asymmetries are further complicated by the adversarial nature of many justice systems, where strategic litigation can exploit technical ambiguities to challenge or exclude digital evidence. Addressing this divide requires not only capacity building but also epistemological dialogue between law and computer science, enabling shared vocabularies and standards of proof.

The absence of standardised forensic protocols in many developing and transitional legal systems amplifies these difficulties. Allah Rakha (2024), examining the experience of Uzbekistan, found that fragmented procedural guidelines and limited institutional oversight undermine both domestic investigations and cross-border cooperation. Without harmonised rules on evidence collection, preservation, and authentication, digital forensics becomes an ad hoc practice vulnerable to contestation. The problem is particularly acute in cases involving cybercrime and transnational offences, where evidentiary material may traverse multiple jurisdictions with divergent admissibility standards. Similar conditions exist across Central Asia, the Western Balkans, and parts of Sub-Saharan Africa, where judicial systems are modernising without comprehensive digital procedural codes. The result is a patchwork of practices that compromises the comparability and credibility of digital evidence in international proceedings.

Recent experimental research has turned to technological hybridisation as a response to evidentiary fragility. AlKhanafseh and Surakhi (2024) developed a model that integrates blockchain with Long Short-Term Memory (LSTM) steganography to enhance both integrity and confidentiality. Their framework segments evidence into smaller digital fragments, embeds them linguistically using steganographic algorithms, and records their transfer within an immutable blockchain ledger. This approach enhances resistance to tampering while maintaining verifiability. The authors reported improvements in scalability and reduced data corruption relative to centralised databases, suggesting that algorithmic innovation can reconcile the competing imperatives of security and manageability. However, the translation of such models into judicial contexts remains uncertain, as courts have yet to develop procedural doctrines that recognise algorithmic integrity as a sufficient substitute for human attestation.

Parallel debates are emerging in the field of forensic accounting and financial investigations, where digital evidence intersects with regulatory compliance. Awwad and Abdelsattar (2025) analysed the Saudi Arabian experience under its 2021 Law of Evidence and 2023 SOCPA standards, observing that the reliability of digital financial data depends heavily on formal professional certification and institutional oversight. Their findings demonstrate how legal recognition of digital audits and electronically stored information (ESI) can strengthen evidentiary credibility. Yet the model also underscores the fragility of systems reliant on human discretion, as procedural lapses or undocumented updates to accounting software can invalidate entire chains of evidence. This interplay between professional ethics and technological governance reflects a broader shift towards multi-disciplinary accountability in digital justice.

The procedural implications extend to the protection of fundamental rights, particularly the right to a fair trial. Stoykova (2023) analysed European jurisprudence and argued that fairness in digital investigations requires procedural equality between the prosecution and defence in accessing, interrogating, and challenging digital evidence. Many national frameworks, however, lack mechanisms enabling defendants to verify the forensic methods used against them. The imbalance is especially acute in automated or AI-assisted investigations, where algorithmic decision-making can obscure the evidentiary basis of a case. Stoykova (2023) proposed two groups of rules derived from equality of arms and the presumption of innocence, aimed at embedding fairness principles directly within digital forensic practice. Her work demonstrates that the legitimacy of digital evidence cannot rest solely on technological credibility; it must also satisfy the normative demands of transparency, contestability, and accountability.

A related problem concerns the reproducibility and validation of forensic results. Stoykova and Franke (2023) identified inconsistencies in forensic methodologies that undermine reproducibility across laboratories. Their Reliability Validation Enabling Framework (RVEF) establishes a structured model for evaluating the reliability of digital forensic techniques at three levels: technology, method, and application. By requiring detailed documentation of each stage, RVEF seeks to make forensic validation transparent to both scientific and judicial audiences. The framework represents a critical step towards bridging the epistemic divide between legal adjudication and scientific experimentation. Its potential lies in institutionalising procedural reliability as a measurable attribute, thereby offering courts a principled basis for evaluating expert testimony.

4 Admissibility of digital evidence

4.1 Legal frameworks governing digital evidence

The admissibility of digital evidence rests upon an interlocking set of legal and technical criteria that national and international instruments seek to define and operationalise. Across the literature, there is firm agreement about a small number of legal prerequisites that courts almost everywhere apply in practice: proper legal authorisation for search and seizure, relevance to issues in the case, demonstrable authenticity, preserved integrity, and the competence of forensic procedures and experts. These core requirements are not merely rhetorical. They appear explicitly in teaching and practitioner resources such as the UN Office on Drugs and Crime cybercrime teaching module, which sets out a practical three-phase assessment model of digital evidence admissibility that separates assessment of legal authority from technical review and final judicial determination. The module, therefore, consolidates what is now an established finding: courts evaluate admissibility as a hybrid legal-technical judgement rather than a single doctrinal test. Comparative doctrinal work shows how this hybrid test is implemented unevenly in national statutes and case law. Leroux's (2004) comparative analysis of electronic evidence law in Europe identified the familiar pattern: statutory or common law frameworks attempt to map older evidentiary concepts such as the best evidence rule, hearsay and authenticity onto new forms of electronic data, but courts confront persistent conceptual frictions when they do so. Tanzania provides an instructive concrete example of this tension. The Electronic Transactions Act and the amended Evidence Act attempt to place data messages on the same footing as paper documents and supply factors for assessing evidential weight, while the High Court’s case law has oscillated between literal compliance with statutory language and the judicial insistence on practical certificates of system reliability. The detailed exposition of Tanzanian statutes and case law in Makulilo's (2016) study illustrates an important practical lesson: statutory modernisation alone does not resolve the evidentiary problems that arise in practice; judicial practice, prosecutorial habits and institutional capacity mediate statutory effects.

Technical models and methodological frameworks respond to these legal frictions in two different registers. One set of interventions is procedural and institutional: harmonised admissibility assessment models and accreditation of forensic laboratories. Antwi-Boasiako and Venter's (2017) Harmonised Model for Digital Evidence Admissibility Assessment (HM-DEAA), featured in the UNODC module (United Nations Office on Drugs and Crime, 2025), is an example of a harmonisation attempt that formalises the three-phase approach into assessment, consideration and determination steps. That model is practical insofar as it instructs courts to verify legal authority first, then to scrutinise the tools, methods and qualifications underpinning the evidence. The success of this design is its clarity: by separating legal and technical questions, it reduces conflation of admissibility and weight. The remaining problem is operational. Many jurisdictions lack accredited laboratories, validated toolsets, or a pool of qualified expert witnesses to carry out the HM-DEAA steps reliably. A second set of interventions is technical and focuses on tool validation, reproducibility, and documentation. Granja and Rafael (2017) examined preservation models and found that conventional archival strategies such as periodic data migration and manual documentation are already strained by volume and format heterogeneity. Their analysis leads to a practical conclusion that is now well supported by empirical studies: preservation must be conceived as a forensic lifecycle comprising generation, capture, hashing or timestamping, secure storage and provable retrieval, rather than as episodic archival activity. This lifecycle approach demands routine validation of tools and explicit documentation of every handling event so that courts can trace provenance and assess tampering risk.

The question of tool validation returns us to methodological debates about commercial versus open source forensic tools and the standards required for judicial acceptance. Recent experimental work proposes structured validation frameworks that aim to satisfy legal admissibility standards familiar in jurisdictions influenced by Daubert-style reliability testing. Ismail and Akram Zainol Ariffin's (2025) open-source forensic-readiness framework proposes three phases: basic forensic process controls, result validation with repeatability metrics, and readiness measures for legal scrutiny. Their controlled experiments comparing open source and commercial suites provide an empirical counterweight to the common judicial preference for commercially validated tools: with proper validation protocols, open source tools can produce repeatable, legally defensible artefacts. The policy implication is concrete and operational: courts and legislatures that block or disprefer open source options on the grounds of tool provenance risk imposing unnecessary cost barriers without commensurate improvement in evidentiary quality. Cross-cutting bottlenecks emerge from the empirical and doctrinal literature and merit emphasis because they are solvable only through combined legal and technical reform. First, the institutional capacity gap: many jurisdictions enact admissibility rules but do not invest in accredited laboratories, continuous tool-validation programmes, or specialist prosecutors and defence experts who can litigate technical disputes. Second, standardisation deficits: the multiplicity of national evidentiary tests and divergent procedural practices generate friction in transnational cases, undermining mutual legal assistance and the transfer of electronic exhibits. Third, the epistemic asymmetry between technologists and magistrates: without common documentation standards and transparent validation procedures, judges are forced to weigh digital evidence with limited means to interrogate underlying methods, creating inconsistent case outcomes. These bottlenecks are identified repeatedly across practitioner surveys and comparative law studies, which suggests they are not isolated empirical anomalies but systemic constraints. The literature distinguishes well between established legal practice and plausible reform hypotheses. It is a fact that courts require demonstrable legal authorisation and will scrutinise authenticity and integrity; the UNODC module codifies this as practical pedagogy for prosecutors and judges. It is also well established that validated documentation and reliable laboratory processes increase admissibility and evidentiary weight. By contrast, some of the more ambitious proposals remain hypotheses requiring further field testing. Examples include the claim that universal adoption of blockchain timestamping will render chain of custody disputes largely obsolete, and the proposal that validated open source stacks will rapidly democratise forensic capability worldwide. These are technically plausible, yet their real-world effect depends on complementary legal recognition, institutional investment and interoperability standards. The immediate research and policy priorities are thus clear. Empirical validation studies, accreditation schemes and harmonised admissibility guidance that link legal tests to specific technical validation steps represent the most promising pathway from hypothesis to practice (Figure 2).

4.2 Challenges in admissibility

The persistent challenges surrounding the admissibility of digital evidence reflect a structural imbalance between the speed of technological change and the capacity of legal and forensic institutions to adapt. Although statutory and procedural frameworks now exist in most jurisdictions, they remain fragmented and often fail to provide clear, standardised methods for managing digital traces through their evidentiary lifecycle. Recent case-based and empirical studies illustrate that admissibility disputes often arise not from the absence of law but from its inability to capture the complexity and volatility of digital artefacts. A detailed case analysis by Bérubé et al. (2025) provides a vivid account of these tensions. In a terrorism-related trial, the authors identify three interrelated categories of challenges: operational, technical, and managerial. Operationally, investigators face what the study conceptualises as the “9Vs” of digital forensics, namely, volume, variety, variability, velocity, volatility, veracity, virtue, value, and visualisation. The growing volume of data generated by digital devices far exceeds the capacity of investigative teams to extract and classify relevant material within judicial timelines. The diversity of data formats and sources adds another layer of complexity, as evidence can originate from unstructured media such as messaging platforms, encrypted cloud storage, or Internet of Things devices, each requiring different acquisition protocols. The variability of digital traces, shaped by differences in device configurations and contextual use, undermines reproducibility and complicates the establishment of methodological standards. Bérubé et al. (2025) demonstrate that this combination of scale, heterogeneity, and inconsistency produces uneven investigative practices that, in turn, challenge judicial assessment of reliability. These findings resonate with the broader forensic science perspective offered by Klasén et al. (2024), who argue that the pace of technological development has outstripped the institutional ability of forensic laboratories to remain current. Their analysis situates digital forensics within an ecosystem of emerging tools such as artificial intelligence, digital twins, and autonomous data-gathering systems. Although these tools enhance analytical capability, they also multiply potential sources of error. Many laboratories struggle to maintain the validation cycles, training, and technical updates required to ensure evidentiary defensibility. The Swedish case of Digital Forensics Sweden (DFS) demonstrates partial progress, where shared resources and cooperative validation improve consistency. However, even in advanced systems like DFS, difficulties persist in safeguarding privacy and maintaining interpretive clarity, illustrating that technological sophistication alone does not guarantee admissibility (Figure 3).

Comparative insights from John (2021) further reveal that legislative reform alone cannot resolve procedural ambiguities. In Tanzania, the Electronic Transactions Act codified basic authenticity requirements but failed to clarify the foundational process for introducing electronic evidence in court. Judicial rulings remain inconsistent regarding the degree of expert involvement required to validate digital records. Earlier cases excluded potentially probative evidence simply because it lacked expert certification or proper documentation. This aligns with the findings of Yeboah-Ofori (2020), who emphasises that inadequate chain of custody, insufficient documentation, and lack of procedural accuracy frequently render evidence inadmissible. They study identifies four interdependent qualities required for acceptance: authenticity, accuracy, completeness, and persuasiveness. Their analysis highlights that evidentiary reliability depends as much on procedural discipline as on technological accuracy. A unifying theme across these studies is the inherent fragility of evidentiary integrity in the digital age. Many forms of digital data are transient and must be captured within narrow timeframes. Yet procedural safeguards such as judicial authorisations, chain-of-custody documentation, and forensic validation slow the collection process. When traces are lost or altered before proper acquisition, admissibility cannot even be tested. Conversely, reliance on unverified or proprietary forensic tools without transparent validation enables the defence to challenge reliability and authenticity. This dual tension between the urgency of collection and the necessity of validation epitomises the admissibility problem in modern digital forensics. What has worked effectively are integrative frameworks that combine legal oversight with technical standardisation. National cooperative models such as DFS, along with the structured validation systems proposed by Bérubé et al. (2025), demonstrate measurable improvements in consistency and trustworthiness. What continues to fail are fragmented or opaque systems where investigative discretion replaces codified procedure or where courts accept or reject evidence without understanding its technical foundations. The collective evidence from recent scholarship therefore points towards a single imperative: the harmonisation of forensic and legal processes through transparent, validated, and interoperable mechanisms that evolve concurrently with technology rather than in reaction to it (Table 1).

TABLE 1. Analytical mapping of digitalisation risks, mitigation pathways and justice-system implications in criminal proceedings.

5 Integration of blockchain technologies into law enforcement

In this review, blockchain denotes a distributed ledger architecture in which authorised nodes maintain a shared chronological record of evidentiary metadata, with each entry linked to prior entries through cryptographic hashes and validated through a defined consensus rule. Hashing functions as a fingerprint of a file or event; timestamping records when the event was registered; consensus determines which institutional actors may validate entries; and smart contracts are programmable rules that can trigger procedural actions only when predefined conditions are satisfied. These concepts are consolidated here because their legal value depends less on technical novelty than on whether they support authenticity, integrity, traceability, privacy protection and contestability in criminal proceedings (Guttman et al., 2022).

For law-enforcement purposes, blockchain is therefore best understood as a controlled evidentiary verification infrastructure rather than a general-purpose public ledger. Public blockchains maximise open verification but are rarely appropriate for criminal justice data because unrestricted participation, permanent visibility and uncertain jurisdictional governance conflict with confidentiality, victim protection, investigative secrecy and data-protection obligations. Permissioned or consortium blockchains are more compatible with criminal proceedings because validator participation can be limited to legally accountable institutions such as police agencies, forensic laboratories, prosecution services, courts and authorised oversight bodies. In these systems, governance design is as important as cryptography: node admission, validator accountability, access permissions, audit authority, key management, dispute resolution and system updates determine whether the ledger can support evidentiary trust (Shahaab et al., 2021).

The most legally defensible architecture separates evidence storage from evidence verification. Large or sensitive evidentiary files are retained off-chain in secure forensic repositories, while the ledger records hashes, timestamps, custody events, access logs, warrant or authorisation references, disclosure milestones and validation outcomes. This on-chain/off-chain model reduces storage burden, limits exposure of personal data and enables courts to verify whether a file presented in proceedings corresponds to the preserved forensic record without placing the file itself on an immutable ledger. Consensus models in justice settings therefore prioritise accountability and finality over anonymous participation, and practical designs commonly favour Byzantine fault-tolerant, proof-of-authority or consortium-based consensus subject to transparent rules for validator independence, error correction, audit review and legal challenge. These consolidated definitions frame the subsequent discussion, allowing the subsections to focus on operational applications, legal effects and implementation risks rather than repeating blockchain fundamentals (Guttman et al., 2022; Shahaab et al., 2021).

5.1 Evidentiary and operational applications of blockchain in criminal justice

In criminal justice, the operational value of blockchain lies in verifying evidentiary events across institutions rather than in the generic idea of decentralisation. The principal operational applications are evidence metadata logging, forensic workflow auditing, controlled data sharing, smart-contract-assisted procedural triggers and asset tracing in corruption or financial-crime investigations. Evidence integrity remains the most mature application. Patil et al. (2024) demonstrate that manual chains of custody remain prone to human error, evidence tampering and procedural inconsistencies. Their proposed chain-of-custody model records each evidence-handling event, from collection to courtroom presentation, as a time-stamped action validated by authorised participants. The legal and operational significance is that courts and parties can audit whether custody, access and transfer events occurred in the expected sequence, reducing disputes over provenance without relying solely on paper documentation. However, Patil et al. (2024) caution that such systems require cross-institutional cooperation between police, forensic laboratories and judicial bodies. Without harmonised technical standards and inter-agency interoperability, blockchain tools may create parallel logs that are technically secure but procedurally fragmented, thereby weakening the intended gain in evidentiary consistency (Figure 4).

The structural sophistication of blockchain in judicial contexts is further explored by Chen et al. (2020), who propose a consortium model for generating and validating electronic evidence within accredited judicial and investigative institutions. Because node participation is restricted to legally recognised actors, the model translates the technical verification layer into a procedurally accountable workflow for evidence submission, review and validation. Their experimental implementation suggests potential improvements in traceability and workflow efficiency; judicial effects require real-world validation. Nonetheless, Chen et al. (2020) note that such systems face scalability constraints because high-volume evidentiary environments require substantial computing resources, technical expertise and institutional coordination. The model also depends on infrastructure and legal readiness, which creates barriers in international cases where participating jurisdictions differ in their capacity to recognise or operate comparable verification systems.

In parallel, blockchain integration into digital forensic practices introduces new methods for ensuring the authenticity and traceability of forensic processes. Al-E’mari et al. (2024) develop a framework that embeds blockchain into digital forensic workflows by registering key forensic actions as verifiable audit events. The operational impact is the production of a traceable record from acquisition to reporting, enabling investigators to demonstrate continuity and procedural compliance when evidence is challenged in court. The authors report gains in accountability and transparency but also acknowledge limitations. Sensitive metadata recorded in immutable audit trails may create privacy risks in investigations involving personal or confidential data. Further, comprehensive event logging can increase computational burden and delay time-sensitive investigations, indicating a trade-off between evidentiary precision and operational efficiency.

Beyond forensic applications, smart-contract-assisted workflows offer opportunities to automate limited procedural compliance and evidentiary management tasks. Zang et al. (2022) argue that criminal justice processes such as evidence submission, warrant validation and disclosure management can be automatically triggered when defined procedural conditions are met. The practical value lies in reducing administrative delay and human error while making compliance steps more consistent and auditable. The authors emphasise that blockchain-based records must still satisfy established legal principles such as authenticity, legality and relevance, and they propose using smart contracts to support evidentiary standards such as best evidence and corroboration. However, Zang et al. (2022) warn that automation must not displace judicial discretion or due process. Overreliance on algorithmic enforcement can generate rigid procedural outcomes that fail to account for context, proportionality or equitable considerations, making regulatory oversight and human review indispensable.

The utility of blockchain in asset tracking and anti-corruption efforts has also gained attention. Ayeboafo et al. (2025) investigate Ghana’s readiness for blockchain adoption in anti-corruption frameworks using the Technology Acceptance Model. Their analysis reveals that perceived usefulness and ease of use are key determinants of institutional adoption, surpassing even regulatory or infrastructural considerations. Blockchain enables continuous monitoring of asset transfers and ownership histories, providing law enforcement with a transparent, tamper-resistant record of financial movements. The study demonstrates that such systems can deter illicit enrichment and facilitate asset recovery by ensuring that relevant transactions can be verified by authorised stakeholders. Public verifiability is not inherent in permissioned law-enforcement systems. However, Ayeboafo et al. (2025) point out that without explicit legislative recognition of blockchain-generated data as admissible evidence, these technological gains remain largely symbolic. This finding illustrates that successful integration of blockchain into criminal justice not only requires technical capability but also corresponding legal reform and institutional trust.

A broader technical and investigative dimension is provided by Atlam et al. (2024), who conduct a systematic review of blockchain forensics and evaluate how distributed ledgers can support investigative transparency and evidentiary traceability. Their analysis identifies growing use of blockchain records to trace illicit activity and to preserve integrity-sensitive investigative metadata. The evidentiary benefit is strongest when ledger records help reconstruct the sequence of transactions, access events or analytical steps. However, immutability also complicates the correction of errors and the handling of false, incomplete or maliciously inserted information. The same architecture also creates a persistent tension between transparency and privacy because investigators must link ledger traces to real-world identities without unnecessary exposure of personal data. Atlam et al. (2024) therefore call for privacy-preserving blockchain architectures that maintain evidentiary reliability while respecting fundamental rights, a balance that remains unresolved in most operational applications.

Across these operational domains, the reviewed forensic and technological studies show that blockchain can support collaboration among law enforcement agencies, forensic analysts and judicial institutions when it is embedded in accountable procedure. Comparative evaluation of these frameworks indicates that its effectiveness depends on linking procedural documentation with technical validation in a verifiable audit environment. The findings of Patil et al. (2024), Chen et al. (2020), Al-E’mari et al. (2024), Zang et al. (2022), Ayeboafo et al. (2025), and Atlam et al. (2024) collectively indicate that blockchain can operate as an evidentiary safeguard when it verifies custody, access and procedural milestones across diverse justice functions. However, the studies also converge on the point that technical safeguards require legal standardisation, inter-agency coordination and judicial education. Without those institutional conditions, blockchain’s contribution remains a promising but incomplete tool rather than a self-sufficient solution for fairness, transparency and trust in criminal proceedings.

5.2 Prospects, constraints, and implementation risks

The regulatory integration of blockchain into law enforcement and judicial systems remains constrained by implementation maturity, legal uncertainty and governance design. The strongest evidence concerns tamper-evident metadata logging in controlled environments, while cross-border interoperability, automated procedural enforcement and public-facing accountability remain emerging rather than settled capabilities. Kesarkar (2024) demonstrates that immutable, time-stamped ledgers enhance evidentiary integrity throughout legal procedures, from data collection to courtroom presentation, by reducing tampering and strengthening accountability. These benefits are particularly evident in systems where blockchain underpins forensic documentation or interagency coordination, improving traceability and procedural trust. Smart contracts expand these capabilities by enabling automated enforcement of legal obligations, such as monitoring bail compliance or validating contractual performance, thereby reducing administrative inefficiencies. Yet these technological advancements are accompanied by ethical and technical limitations related to scalability, data visibility, and institutional control. Public blockchains promote transparency but risk violating confidentiality requirements, while private or consortium models restrict public verifiability while enabling controlled, auditable verification by authorised participants. Across the literature, it is evident that these technical innovations encounter legal and regulatory friction. Zhuk (2025) identifies a structural tension between blockchain’s immutability and the legal system’s need for adaptability, where permanent records conflict with procedural rights such as correction or deletion. The pseudonymous nature of blockchain also complicates accountability and attribution in criminal contexts, making cross-border evidence authentication difficult. Jurisdictional complexity intensifies when transactions span multiple territories governed by divergent data protection regimes such as the GDPR, which provides a qualified right to erasure subject to statutory exceptions. Technical proposals like reversible cryptography or layered access protocols attempt to address these issues, yet their implementation remains largely experimental and legally untested.

Theoretical and empirical research converge on the insight that blockchain’s socio-technical structure challenges traditional hierarchies of legal authority. Hacker et al. (2019) argue that decentralised systems defy command-based regulation, necessitating governance models built on interoperability and consensus rather than enforcement. Yeoh (2017) cautions that regulatory ambiguity leads to fragmentation and inconsistent enforcement across jurisdictions, while Cumming et al. (2019) warn that overregulation can suppress innovation just as regulatory inertia can foster systemic vulnerability. Guo (2017) and Spring (2019) demonstrate that intellectual property and evidentiary admissibility remain areas of legal uncertainty, where the reliability of blockchain-based records is undermined by procedural incompatibility in court systems. Smart contracts and jurisdictional coherence further illustrate the uneven maturity of blockchain regulation. Durovic and Lech (2019) and Dwivedi et al. (2022) show that while automated code-based contracts facilitate compliance, they often fail to satisfy legal concepts such as consent, consideration, and enforceability. Explicit statutory recognition remains uneven, while many jurisdictions apply existing contract law to smart-contract arrangements. This selective adoption creates inconsistencies in cross-border digital transactions, particularly when contract execution relies on automated triggers beyond human review. Möslein (2018) and Jamal et al. (2019) highlight that blockchain’s borderless operation erodes traditional jurisdictional boundaries, challenging the enforcement of national laws and complicating evidence admissibility across legal systems. The literature therefore underscores that technological precision must be accompanied by regulatory convergence if blockchain is to achieve sustainable legal integration.

Identity management represents one of the most advanced yet controversial domains of blockchain deployment in legal and administrative settings. Traditional identity systems rely on centralised verification, while blockchain-based identity models distribute credential control and enable tamper-resistant authentication. In law-enforcement contexts, however, decentralised identity must comply with jurisdiction-specific rules on financial services, voting, access to public benefits, anti-money-laundering reporting and criminal investigation. Statutory identity verification requirements compel blockchain systems to integrate biometrics, digital signatures, multi-factor authentication, revocation mechanisms and data-minimisation controls. The tension between decentralisation and compliance remains unresolved, but self-sovereign identity architectures, interoperable trust frameworks and public-sector identity programmes demonstrate that blockchain-based credentials can support access control and privacy governance when embedded within clear institutional authority. Their transferability across diverse legal systems remains limited by unequal administrative capacity, incompatible data-protection standards and uneven recognition of digital credentials (Jamal et al., 2019; Malhotra et al., 2022).

Closely connected to identity verification are the regulatory imperatives of Anti-Money Laundering (AML) and Know Your Customer (KYC) compliance, which remain central to the legitimacy of blockchain-based legal and financial applications (Thommandru and Chakka, 2023). The Financial Action Task Force (FATF) (Pavlidis, 2023) identifies material money-laundering and terrorist-financing risks associated with virtual assets and requires risk-based controls for VASPs. Corresponding regulations, such as the European Union’s Fifth Anti-Money Laundering Directive and the U.S. FinCEN guidelines (European Commission, 2025; Dixon et al., 2019), mandate AML/KYC compliance for blockchain operators. Blockchain technology can simultaneously facilitate and complicate compliance: decentralised identity systems and cryptographic traceability enhance transparency, while privacy-preserving techniques like zero-knowledge proofs allow selective disclosure of information (Malhotra et al., 2022). Persistent difficulties arise in identifying beneficial ownership and reconciling transparency with data protection. Jurisdictions such as the EU, U.S., and Singapore have responded by imposing registration and reporting obligations on VASPs. Although these requirements introduce administrative complexity, they also stimulate the development of blockchain-based compliance automation, which can reduce transaction costs and improve oversight efficiency (Xu et al., 2017). The convergence of blockchain-enabled identity verification with AML/KYC frameworks, therefore, defines a critical frontier in the evolution of compliant digital ecosystems (Table 2). Implementation failures arise when blockchain is treated as a technical guarantee without a corresponding governance model. A ledger can record custody events immutably, but it cannot confirm that the first entry was accurate, that the seized device was lawfully obtained, that metadata were complete, or that the person uploading the evidence acted without bias or coercion. These data-quality and oracle risks are central to evidentiary reliability because false, incomplete, or unlawfully generated inputs can become permanently embedded in the audit trail. Governance failures also occur when validator control is concentrated in one agency, when access rights are poorly administered, when key management procedures are weak, or when there is no independent mechanism for contesting ledger entries. In these conditions, blockchain may reproduce institutional asymmetries rather than solve them.

TABLE 2. Blockchain-enabled law-enforcement applications mapped to technical mechanisms, operational value, and legal-ethical risks.

Smart contracts introduce a further category of legal and technical risk. Coding errors, ambiguous legal logic, malicious dependencies, insecure upgrade functions, and poorly tested automated triggers can generate actions that appear procedurally regular on the ledger while remaining legally defective. Automated notification, disclosure, asset freezing, or warrant-validation functions therefore require human override, formal auditability, and clear rules for responsibility when code produces unintended consequences. Scalability and cost-benefit concerns are equally material. High-volume evidence environments generate large numbers of custody events, access records, and validation requests; without careful system design, transaction latency, storage overhead, network maintenance, cybersecurity costs, and staff training may exceed the operational gains. Blockchain adoption is therefore most defensible when deployed for high-value evidentiary metadata, inter-agency verification and cross-institutional audit trails rather than for indiscriminate storage of all case data (Zang et al., 2022; Dwivedi et al., 2022; Möslein, 2018).

The most difficult legal conflicts concern privacy, erasure, jurisdiction, and evidentiary recognition. The GDPR and comparable data-protection regimes recognise rights to rectification, restriction and erasure, while blockchain systems are designed to preserve records permanently. This tension can be reduced through off-chain storage, deletion of underlying files, cryptographic erasure, chameleon hashes, zero-knowledge proofs and selective disclosure, but the legal sufficiency of these techniques remains unsettled in many jurisdictions. Cross-border evidence transfer adds further complexity because validator nodes, cloud repositories, victims, suspects, and courts may fall under different national laws. A blockchain record that is technically verifiable in one jurisdiction may still face admissibility objections elsewhere if rules on search authority, expert testimony, data localisation, disclosure to the defence, or recognition of digital signatures differ. These conflicts demonstrate that blockchain-based evidence requires harmonised legal frameworks and procedural doctrines capable of recognising ledger records without weakening the right to challenge them (Zhuk, 2025; Belen-Saglam et al., 2023; Yeoh, 2017).

6 Case studies in integrating blockchain technologies into law enforcement practice

Globally, various jurisdictions are testing blockchain technology to improve the integrity, transparency, and efficiency of law enforcement and criminal justice systems. Kazakhstan has positioned itself as one of the most proactive post-Soviet states in integrating digital technologies into its criminal justice and law enforcement systems. This modernisation effort is guided by the national “Digital Kazakhstan” state programme (2018–2022), which explicitly sought to transform government functions through the establishment of a digital infrastructure for public service delivery (Ondashuly, 2018). A central element of this initiative is the development of an integrated “electronic justice” system designed to improve efficiency, accessibility, and transparency in judicial processes. A key reform within this framework has been the introduction of the electronic criminal case (e-CC) format, enabled by amendments to the Criminal Procedure Code, which allow pre-trial and judicial proceedings to be conducted entirely in digital form (Kuzhabayeva et al., 2019). The operational core of this reform is the e-CC module, a component of the Uniform Register of Pre-trial Investigations (URPI), which manages the full lifecycle of a criminal case from the initial registration of an offence to the final court decision. All documents are digitised as certified PDFs with electronic signatures, and authorised personnel are granted real-time access through secure digital channels. Transparency is further enhanced through the “Public Sector” portal, which allows participants in criminal proceedings to access case materials remotely, submit petitions, and file complaints (Kuzhabayeva et al., 2019). Adoption of these tools has been rapid, and by 2022, the General Prosecutor’s Office reported that the majority of criminal cases were being processed electronically (Dalmatov et al., 2024). Ondashuly (2018) notes that Kazakhstan’s judicial digital backbone consists of several interconnected platforms. The “Torelik” Unified Information-Analytical System automates workflow management and procedural deadlines across all courts. Public interaction is supported through the “Court Cabinet” service, which by early 2018 had registered hundreds of thousands of users and handled the majority of court applications electronically. Oversight is maintained through the Supreme Court’s Situation Centre, which conducts real-time monitoring of courtrooms across the country using continuous audiovisual recording to detect procedural irregularities and promote judicial discipline.

In the United States, blockchain is being explored as a tool to address persistent inefficiencies within the criminal justice process, particularly those contributing to mass incarceration, pretrial detention, and wrongful convictions. Rojas (2023) emphasises that manual and fragmented record-keeping systems often delay case processing and impede accountability. Blockchain introduces a mechanism for secure and immutable case management, offering consistent access to verified data across agencies. Proposed applications include statewide pretrial data systems, automated court tracking, and digital-evidence management platforms. These initiatives strengthen data reliability, reduce administrative delays, and ensure that case decisions are based on verified records. Such efforts demonstrate the role of blockchain in reinforcing procedural fairness and transparency in criminal justice operations. In China, blockchain has been studied or proposed as a means of strengthening disciplinary and supervisory functions within law enforcement bodies (Wei and Gu, 2020). The system facilitates traceable and tamper-resistant handling of investigative materials, such as case clues, evidence trails, and inter-agency communications. It integrates distributed ledgers and timestamping mechanisms to enhance the credibility of administrative actions. This approach enables consistent audit trails, limits manipulation risks, and supports real-time cross-departmental collaboration. The Chinese experience illustrates how blockchain can function as a digital compliance and oversight tool, improving accountability in institutional conduct.

In Nigeria, blockchain has been proposed as a practical mechanism for improving evidence handling and chain-of-custody management (Enokie, 2025). Issues such as document tampering and data loss frequently compromise the credibility of forensic and investigative evidence. Blockchain-based registries address these problems by securing metadata, authenticating digital evidence, and supporting automated record verification through smart contracts. These innovations could reduce opportunities for corruption and could strengthen judicial confidence if legally and operationally validated. However, progress depends on regulatory modernisation, infrastructure readiness, and professional training. In the Russian Federation, blockchain integration forms part of a national strategy to modernise judicial and administrative processes (Zatsepin et al., 2020a). Courts already employ advanced digital systems, including electronic filing, cryptographic document validation, and virtual hearings. Blockchain is viewed as an extension of these efforts, particularly for authenticating digital evidence and procedural documents. The proposed model envisions a unified blockchain platform connecting judges, advocates, experts, and law enforcement agencies within a single digital framework. This network would enable real-time validation of procedural actions while protecting confidentiality and reducing bureaucratic inefficiencies. Implementation challenges remain, primarily due to infrastructure costs and concentration of resources among a few major institutions, yet the initiative demonstrates a structured approach to judicial digitalisation.

In Japan, blockchain applications intersect with private international law, introducing unique regulatory challenges in identifying responsible parties and determining applicable jurisdiction (Morishita, 2023). Courts must navigate complex issues regarding the admissibility of blockchain-derived evidence and the enforcement of smart contract terms. This legal analysis highlights questions concerning data localisation, evidentiary recognition, and cross-border cooperation. The legal debates illustrate how blockchain adoption in law enforcement contexts requires synchronised regulatory and technical frameworks that preserve legal certainty while encouraging innovation. A more recent development comes from Central and Eastern Europe, where blockchain has been applied to anti-money laundering efforts across the V4 countries (Poland, the Czech Republic, Hungary, and Slovakia) and Ukraine. Nita (2025) provides a detailed comparative analysis of blockchain’s role in financial crime prevention and regulatory harmonisation in this region. Blockchain-based AML systems leverage features such as real-time transaction monitoring, automated anomaly detection, and smart contracts that can freeze or flag suspicious funds automatically. In Poland and the Czech Republic, comprehensive regulatory frameworks impose AML/KYC and reporting obligations on relevant entities; they do not generally mandate blockchain-supported KYC verification and reporting to national financial intelligence units. Hungary and Slovakia have faced implementation challenges due to technological and resource constraints, while Ukraine has adopted blockchain measures to enhance transparency in cryptocurrency transactions and reduce corruption risks. This regional experience underscores blockchain’s dual function as a law enforcement instrument and a regulatory compliance mechanism. On the one hand, blockchain facilitates cross-border cooperation by providing tamper-evident transaction records that may be made accessible to authorised financial-intelligence and law-enforcement bodies under applicable law enforcement agencies. On the other hand, it exposes gaps in harmonisation and capacity, such as differences in implementing FATF’s “travel rule” and regulating non-custodial wallets. These findings highlight the importance of coordinated governance, technical interoperability, and international collaboration between institutions such as Europol and FATF.

Taken together, the case studies show that blockchain adoption in criminal justice remains uneven across jurisdictions and application domains. Kazakhstan and Russia provide stronger evidence of broader judicial digitalisation, but blockchain-specific deployment is still more clearly articulated as an extension of electronic justice infrastructure than as a fully mature evidentiary system. The United States, Nigeria, and China illustrate operationally plausible applications in case management, chain-of-custody protection, and disciplinary oversight, while several initiatives remain conceptual, pilot-based, or dependent on legislative recognition. Japan and the V4-Ukraine experience reveal that cross-border legal effects, AML compliance and jurisdictional recognition are central to practical deployment. This evidence profile supports cautious optimism: blockchain is most established as a tool for metadata integrity and auditability, emerging as a platform for regulated inter-agency coordination, and still hypothetical as a comprehensive replacement for conventional evidentiary governance (Nita, 2025; Wei and Gu, 2020; Zatsepin et al., 2020b).

7 Algorithmic accountability and the future of autonomous justice systems

Advances in the literature converge on two clear, evidence-backed observations. First, machine learning systems deployed in high-stakes domains are prone to reproducing social biases and producing opaque decision logic, which materially affects fairness and legitimacy; this is well documented by Horneber and Laumer (2023) and by Hayward and Maas (2021). Their empirical and literature-grounded accounts show that risk-scoring, predictive policing, and automated classification can systematically disadvantage minority groups when training data reflect historical inequalities. Second, blockchain and distributed ledger technology can provide tamper-evident logs under defined consensus, access-control, and governance arrangements of transactions and artefacts, a property that systems designers can exploit to create auditable chains of provenance for data and model outputs. Demertzis et al. (2023) and related engineering work demonstrate that recording metadata, model versions, input hashes, and decision outputs on permissioned ledgers makes later verification technically straightforward, and this capability has been validated in prototype systems and proof-of-concept deployments.

Where the studies diverge is in how readily these technical strengths translate into institutional accountability. Busuioc (2021) and Cheong (2024) argue from administrative and legal perspectives that technological transparency by itself will not yield public accountability unless governance structures are adapted. Busuioc shows that public sector adoption of algorithms without new oversight procedures may shift opacity rather than reduce it because existing lines of administrative responsibility remain unchanged. Cheong likewise synthesises legal, ethical, technical, and stakeholder perspectives and finds that transparency must be paired with rights-preserving legal frameworks, independent audit bodies, and public-facing explanation mechanisms for outcomes to be meaningful. By contrast, the engineering literature, represented by Demertzis et al. (2023), tends to emphasise system architectures that combine explainable AI methods with privacy-preserving cryptography, such as homomorphic encryption and differential privacy, and with blockchain audit logs. These engineering proposals are technically promising and specific, yet they remain largely at the prototype stage and have limited evidence about large-scale operational performance and legal admissibility.

On concrete methodologies and system design, the literature yields practical, specific options and also exposes trade-offs. Demertzis et al. specify a stack in which (a) the AI model publishes a signed record of the model version, input hash, and output to a permissioned ledger; (b) explainability tools produce human-readable rationales that are linked to the ledger entry; and (c) cryptographic techniques protect sensitive inputs. This stack addresses traceability and privacy simultaneously, but it increases computational cost and complexity. Radanliev (2025) and Hosseini Tabaghdehi and Ayaz (2025) augment that view with organisational recommendations such as routine algorithmic audits, diverse development teams, and continual model validation. These procedural proposals are actionable but have not yet been validated at scale; their effectiveness will depend on resourcing, legal recognition of audit evidence, and the capacity of courts and oversight bodies to interpret technical audit trails. Conflicting assessments appear around the role of blockchain as a remedy for accountability deficits. Some authors present blockchain as the keystone infrastructure that can convert black boxes into auditable processes by providing immutable logs and smart-contract-mediated workflows. Others caution that ledger-based logging can itself create new risks: permanent records can expose sensitive personal data unless strong privacy-preserving layers are applied, and immutability can complicate lawful redress or correction of erroneous data if appropriate governance channels do not exist. It is also noted that technical fixes are necessary but not sufficient; they call for an integrated approach that combines design, law, and institutional reform. In short, blockchain is a powerful instrument for recordkeeping, but it must be embedded within a human-centred accountability regime. Successes and setbacks across these studies reveal clear design principles and priorities. First, permissioned ledgers should be preferred over public blockchains for justice applications to ensure controlled access and legally accountable governance (Nasir et al., 2024). Second, each automated decision should be accompanied by a linked metadata package that records model identity, data provenance, parameter snapshots, and a summary explanation generated by established XAI tools (Agostinho et al., 2023). Third, privacy-preserving computations should be employed where input confidentiality is required, using methods such as differential privacy for statistical outputs or homomorphic techniques for computations on encrypted evidence, while recognising current performance and implementation constraints (Li et al., 2020). Fourth, legal and procedural mechanisms should be established to convert ledger entries into admissible audit evidence, supported by standardised logging schemas, certified auditors, and training programmes enabling judicial and legal professionals to interpret technical traces accurately (Mei and Duan, 2025). These recommendations are based on existing engineered prototypes and policy analyses and advance the discussion from conceptual proposals to actionable system-level prescriptions.

8 Recommendations

8.1 Development of standardised protocols

The establishment of standardised protocols for the collection, preservation, and presentation of digital evidence is essential to ensuring procedural consistency, integrity, and admissibility across jurisdictions. Both the UNESCO–International Association of Prosecutors Guidelines (UNESCO, 2025) and the U.S. National Institute of Standards and Technology (NIST IR 8387) (Guttman et al., 2022) underscore the need for unified, transparent, and technically sound procedures that preserve evidentiary reliability throughout the digital chain of custody. The UNESCO–IAP framework emphasises legality, proportionality, and the safeguarding of human rights during digital investigations, requiring that digital evidence be collected in a manner that maintains authenticity through secure logging and cryptographic verification, while avoiding excessive data collection that may infringe on privacy. Complementing this, NIST IR 8387 provides detailed technical preservation guidance and considerations for evidence handlers, outlining best practices for the creation and verification of cryptographic hashes, secure storage environments, and long-term data preservation methods. It highlights the importance of using NIST-approved hashing algorithms, separate storage of verification data, and documented procedures for data transfer and storage integrity, ensuring that any modification to evidence can be detected and accounted for. Integrating blockchain should therefore be treated as an additional design option whose governance, interoperability, and legal effects require separate validation. However, both sources caution that such technologies must be implemented within clearly defined governance frameworks to prevent fragmentation and maintain interoperability. International coordination could support future recognition of properly authenticated digital evidence, including ledger-supported records where legally accepted.

8.2 Legal reforms and institutional alignment

Legal frameworks must evolve to reflect the technical and procedural realities introduced by blockchain and other emerging technologies, balancing innovation with regulatory oversight. Dominic Ochigbo et al. (2024) note that, the decentralised and immutable nature of blockchain disrupts traditional legal doctrines rooted in centralised control and territorial jurisdiction, creating gaps in liability attribution, enforcement, and evidentiary recognition. Building on this, Von Hafe et al. (2025) provide a comparative European perspective, showing that Switzerland, Malta, and Liechtenstein use specialised national blockchain frameworks, while the EU's MiCA establishes a separate, EU-wide crypto-asset framework whose implementation and enforcement involve national authorities. This dual insight underscores the tension between regulatory precision and flexibility, as specialised frameworks foster legal certainty and scalable innovation, while generalist approaches, despite creating ambiguity, can paradoxically encourage competitive experimentation. Therefore, procedural laws should be updated to explicitly recognise smart contracts, distributed ledgers, and digital audit trails as legitimate sources of evidence, while embedding principles of transparency, accountability, and due process. Institutional coordination among courts, regulators, and lawmakers becomes essential to harmonise jurisdictional authority, data integrity, and privacy protections, ensuring that blockchain-generated evidence is both legally admissible and technically reliable. Comparative analyses of jurisdictions such as Japan and Switzerland, versus more restrictive regimes like China, further highlight that adaptive, innovation-aligned legal frameworks, when combined with clear institutional protocols, are most effective in integrating blockchain into criminal justice processes while maintaining public trust and safeguarding individual rights.

8.3 Training and capacity building

Training and capacity building are critical for the effective integration of blockchain-generated evidence into criminal justice systems, requiring law enforcement officers, prosecutors, and judges to possess not only technical proficiency but also a nuanced understanding of the ethical, procedural, and evidentiary dimensions of digital evidence. Studies such as Avhad et al. (2025) emphasise the technical imperatives, demonstrating that blockchain-based evidence management systems can ensure immutability, traceability, and secure access control through cryptographic protocols and smart contracts, thereby mitigating risks inherent in traditional, centralised evidence handling. However, the success of such systems depends heavily on user literacy; without rigorous training, officers and judicial personnel may misinterpret blockchain logs or fail to enforce proper access controls, undermining the system’s potential benefits. Complementing this, Hasan et al. (2021) highlight the pedagogical strategies necessary to bridge the gap between emerging digital technologies and judicial practice, proposing modular, scalable curricula in digital forensics that integrate legal theory, cybercrime understanding, and practical investigative skills. While these programs have succeeded in producing structured and updatable educational frameworks, challenges persist in standardising training across jurisdictions and keeping pace with rapidly evolving attack vectors and forensic techniques. Comparing these studies reveals a convergence on the need for interdisciplinary approaches: Avhad et al. (2025) underscore the technological architecture and operational protocols, whereas Hasan et al. (2021) focus on curriculum design and cognitive assimilation of technical knowledge by judicial stakeholders. The synthesis of these perspectives suggests that effective capacity building requires both robust, technically sound systems and systematically designed educational interventions that foster comprehension, critical evaluation, and ethical use of blockchain evidence. Bottlenecks identified include variability in institutional readiness, uneven technical literacy among personnel, and insufficient collaboration between computer scientists and legal educators. Future initiatives should prioritise adaptive training models, scenario-based exercises, and cross-disciplinary partnerships, ensuring that blockchain adoption translates into reliable, legally defensible, and procedurally consistent outcomes.

8.4 Ethical and privacy safeguards

Given blockchain’s configurable visibility and append-only or tamper-evident characteristics. Transparency and practical immutability depend on architecture and governance. Zafar (2025) highlights the complex interplay between blockchain systems and the EU’s General Data Protection Regulation (GDPR), emphasising that decentralisation and immutability challenge conventional compliance frameworks, particularly regarding joint controllership, consent management, and rights to erasure. To address these challenges, technological innovations such as zero-knowledge proofs, chameleon hashes, and permissioned ledgers can enable selective disclosure and privacy-preserving verification without compromising the evidentiary integrity of blockchain records. Complementing this, Azzi et al. (2025) propose a blockchain-based data governance framework, emphasising data classification, segregation, and access control as key mechanisms to secure sensitive information while enhancing usability and operational efficiency. Together, these studies underscore that ethical oversight cannot be purely procedural but must integrate technical, legal, and organisational layers, involving independent ethics committees in all major blockchain initiatives within law enforcement. Such oversight ensures that privacy-preserving measures are systematically applied, fostering public trust, mitigating the risk of data breaches or misuse, and balancing the dual imperatives of transparency and confidentiality in emerging digital evidence practices.

8.5 Digital divide mitigation and resource-sensitive implementation

Recommendations on criminal-justice digitalisation must expressly address the adoption gap between high-income and low-income jurisdictions. Resource-constrained systems should not be expected to implement advanced blockchain, AI or smart-contract platforms before the basic evidentiary infrastructure is reliable. A sequenced pathway is more defensible: courts and law-enforcement agencies should first establish low-cost electronic filing, standardised digital case registers, secure digital evidence repositories, basic hash verification, role-based access control and interoperable metadata templates. Once these foundations are functioning, regional or national shared forensic services, cloud-hosted public-sector platforms, open-source case-management modules and offline-capable access points can extend digital participation without forcing each institution to build a full independent technology stack. Procurement should favour modular, auditable and vendor-neutral systems to reduce lock-in, maintenance burdens and upgrade costs (Heeks, 2021).

Capacity building should proceed alongside infrastructure development because the digital divide is also a skills and governance divide. Judges, prosecutors, investigators, defence lawyers, court clerks and forensic personnel require practical training in digital evidence handling, cybersecurity hygiene, documentation standards, data-protection duties and the limits of automated decision support. International donors and regional justice networks should prioritise training-of-trainers, shared technical standards, pooled procurement and phased pilot evaluation rather than isolated technology donations. In this model, blockchain becomes a later verification layer for high-value evidence metadata and inter-agency audit trails, not the first step of reform. Such a resource-sensitive approach protects access to justice, reduces procedural inequality and clarifies that closing the digital divide requires institutional capacity, sustainable financing and rights-preserving design as much as connectivity (Heeks, 2021).

8.6 Future research agenda

Future research requires a stronger empirical base capable of moving blockchain-enabled criminal justice from conceptual advocacy to validated institutional practice. The first research priority is the design and evaluation of multi-site pilot studies that compare conventional paper-based chain-of-custody systems, centralised digital logs and permissioned blockchain verification under real investigative conditions. This priority is supported by recent chain-of-custody research showing that blockchain can improve traceability and tamper-evident custody logging, but that most implementations remain prototype, review-based or limited to controlled validation rather than full institutional deployment (Nath et al., 2024; Burri et al., 2020; Ahmad et al., 2020). Such studies should measure evidentiary integrity, processing time, error rates, privacy exposure, cost, scalability, user acceptance and litigation outcomes, particularly because existing forensic blockchain models demonstrate technical feasibility while still requiring field testing, operational benchmarking and legal validation across institutional settings (Lusetti et al., 2020; Liu and Zheng, 2024; Philip and Saravanaguru, 2022). A second priority is the development of standardised evidentiary metadata schemas that define the minimum information required for blockchain-supported admissibility, including evidence identifiers, hash values, timestamps, handler credentials, authorisation records, access events, validation status and audit exceptions. This need aligns with digital forensic interoperability research on common cyber-investigation representations, ontology-based evidence exchange and structured chain-of-custody documentation (Nath et al., 2024; Casey et al., 2015; Casey et al., 2017; Biasiotti et al., 2018).

Legal research needs to clarify when blockchain records qualify as admissible evidence, when they merely support evidentiary weight, and how defendants can challenge ledger accuracy, validator governance or technical failures. Comparative legal studies indicate that blockchain evidence should not be treated as a self-sufficient evidentiary category because courts still need to examine authenticity, integrity, attribution, hearsay, expert explanation, off-chain data quality and the procedural context in which the record was generated (Wang et al., 2024; Su, 2025; Wu and Zheng, 2020; Kaya et al., 2026). Comparative work on GDPR compliance, right-to-erasure conflicts, cross-border evidence transfer, data localisation and recognition of smart-contract actions is particularly important because these issues determine whether technically verifiable records can travel across jurisdictions. This research agenda is reinforced by systematic work on the tension between blockchain immutability and GDPR rights, especially the qualified right to erasure, controller-processor uncertainty, and jurisdictional ambiguity in distributed ledger ecosystems (Belen-Saglam et al., 2023). Research on validator governance should also define decision rights, accountability rules, node admission procedures, audit obligations, and appeal mechanisms in permissioned justice ledgers, since blockchain governance failures can undermine both evidentiary reliability and institutional legitimacy (Liu et al., 2022).

Technical research requires privacy-preserving architectures that combine off-chain forensic repositories, on-chain metadata, zero-knowledge proofs, selective disclosure and secure key recovery without weakening contestability. Recent work on blockchain-based judicial evidence preservation supports hybrid architectures in which large or sensitive evidentiary files remain off-chain while integrity proofs, access events and procedural metadata are recorded on-chain (Liu and Zheng, 2024). Privacy-preserving forensic research further indicates that zero-knowledge proofs and selective disclosure mechanisms can help verify claims without exposing unnecessary personal data, although their performance, explainability and legal contestability still require validation in criminal justice settings (Hameed et al., 2025; Ramić et al., 2024). Future technical studies should therefore test whether privacy-preserving blockchain architectures can maintain evidentiary transparency while satisfying proportionality, defence access, auditability and data-protection obligations.

Translational research should focus on judicial training, prosecutor-defence equality of arms, certified blockchain auditors, cost-benefit assessment, procurement models and institutional readiness indicators. Survey evidence from prosecutors and investigators shows that effective use of digital evidence depends on specialist training, prosecutor-investigator coordination and institutional familiarity with technical evidence (Miller, 2023). Fair-trial scholarship also shows that digital evidence governance must protect equality of arms, defence access and the ability to challenge technical methods, especially where the prosecution has stronger access to forensic expertise and digital infrastructure (Stoykova, 2023; de Arcos Tejerizo, 2023). Tool-validation research further demonstrates that admissibility depends not only on technology choice but also on repeatability, validation metrics, documentation and cost-sensitive access to reliable forensic tools, which is especially important for resource-constrained justice systems (Ismail and Akram Zainol Ariffin, 2025). These milestones provide a practical pathway for integrating blockchain into criminal proceedings while preserving fairness, proportionality and judicial independence.

9 Conclusion

Digitalisation is reshaping criminal proceedings by changing the speed, visibility and technical foundations of investigation, prosecution, evidence handling and judicial decision-making. The literature confirms that electronic case management, digital filing, virtual hearings and forensic documentation can improve efficiency, accessibility and institutional transparency when supported by adequate infrastructure, training and procedural safeguards. The evidence is equally clear that digital transformation remains uneven, with low-resource jurisdictions facing persistent barriers in connectivity, procurement capacity, forensic expertise, cybersecurity readiness and user access. Blockchain adds a distinctive verification capacity within this landscape by enabling tamper-evident records of custody events, evidence metadata, access logs, and procedural milestones. Its strongest contribution lies in strengthening authenticity, integrity and auditability through permissioned governance, off-chain evidence storage and on-chain cryptographic verification. This contribution does not eliminate conventional legal requirements; it supports them by making provenance and handling histories easier to verify and challenge. The review also demonstrates that many blockchain applications remain at the pilot, prototype, or conceptual stage. Smart contracts, cross-border evidence ledgers, autonomous compliance triggers and blockchain-supported AI accountability require stronger empirical testing, legal recognition and institutional oversight before they can be treated as mature justice-sector tools. Persistent risks include governance failures, data-quality and oracle errors, smart contract vulnerabilities, privacy conflicts, right-to-erasure disputes, jurisdictional fragmentation, scalability constraints, cost-benefit uncertainty and institutional resistance. A trustworthy path forward, therefore, depends on socio-technical reform rather than technological substitution. Criminal justice systems require harmonised admissibility standards, validated forensic protocols, interoperable metadata schemes, independent audit structures, professional training and privacy-preserving architectures. When these safeguards are present, blockchain can reinforce procedural integrity and judicial trust; when they are absent, it risks adding another opaque layer to already fragile digital evidence systems. The central implication is that digital and blockchain technologies can enhance justice only when they remain subordinate to legality, fairness, contestability, proportionality and human judicial responsibility.

Generative AI statement

The author(s) declared that generative AI was used in the creation of this manuscript. Generative AI tools were used exclusively for limited language refinement, grammatical editing, structural organization, and stylistic enhancement during the preparation of this manuscript. The conceptual framework, theoretical arguments, analytical interpretations, critical discussions, synthesis of the literature, and all scholarly contributions presented in this Review are entirely the original intellectual work of the authors. All references and literature sources cited in the manuscript were independently identified, verified, interpreted, and critically evaluated by the authors using legitimate academic and scholarly sources. The authors maintained full control over the intellectual direction and academic content of the manuscript and take complete responsibility for its accuracy, originality, integrity, and scholarly validity.

Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Footnotes

Edited by: Tapasi Bhattacharjee, Techno India Group, India

Reviewed by: Hazik Mohamed, Stellar Consulting Group, Singapore

Henry Recalde, Israel University, Ecuador

Milind Tiwari, Charles Sturt University Bathurst Campus Truskett Library, Australia