Introduction
The admissibility of scientific evidence in criminal trials involves a disciplinary boundary crossing that the law has always managed imperfectly. A judge who is expert in the interpretation of statutes and the assessment of witness credibility is not necessarily equipped to evaluate the reliability of a DNA profile, the validity of a digital forensic analysis, or the probative weight of a blood spatter reconstruction. Yet these forms of evidence are increasingly central to criminal prosecution, and their mishandling, whether through inadmissible chain of custody gaps, poorly calibrated expert opinion, or inadequate cross-examination by lawyers unfamiliar with the underlying science, can result in either wrongful conviction or wrongful acquittal.
India’s forensic science infrastructure has improved substantially over the past decade, with the National Forensic Sciences University Act 2020 establishing a central institution for forensic science education and research. But the gap between the aspiration of forensic science as a reliable pillar of criminal justice and the reality of forensic laboratory delays, credibility challenges, and inconsistent evidentiary standards remains significant. The pending DNA Technology Regulation Bill, the unanswered questions about digital forensic standards, and the absence of accreditation requirements for forensic laboratories collectively mean that the reliability of scientific evidence in Indian courts depends more on the credibility of individual experts than on institutional quality assurance. This article examines these issues and argues for a comprehensive reform of forensic evidence standards.
Legal Framework
The Bharatiya Sakshya Adhiniyam 2023, which replaces the Indian Evidence Act 1872, retains Section 45’s approach to expert opinion in substantially the same form. Section 45 BSA provides that when the court has to form an opinion on a point of foreign law, science, art, or the identity of handwriting or finger impressions, the opinions of persons specially skilled in such matters are relevant. The standard for admissibility of expert opinion is therefore a broad one: that the expert is “specially skilled” in the relevant field. This contrasts with the more structured admissibility standards in other jurisdictions, which require not merely that the expert is qualified but that the methodology underlying the opinion is reliable.
The application of forensic science to sexual assault prosecutions has statutory underpinning through the provisions introduced in the CrPC following the 2013 Criminal Law Amendment. Section 53A of the CrPC, now corresponding to BNSS provisions, specifically provided for medical examination of the accused in sexual offence cases to collect forensic evidence. The examination was to be conducted by a registered medical practitioner and was to include DNA profiling. Section 164A provided for medical examination of the victim of rape. These provisions recognised that forensic evidence, including DNA, could provide objective corroboration of testimony in cases where the prosecution’s case would otherwise rest primarily on the victim’s account.
The DNA Technology (Use and Application) Regulation Bill 2019 passed the Lok Sabha but as of 2026 remains pending in the Rajya Sabha. The Bill proposes to regulate the use of DNA technology for establishing identity in criminal investigations, missing persons cases, and civil proceedings. It provides for a DNA Regulatory Board, national and regional DNA data banks, and standards for DNA collection, analysis, and storage. The delay in its passage reflects the sensitivity of the issues it engages, including privacy concerns about the retention of DNA profiles in a national database, questions about who may be profiled and under what circumstances, and concerns about the potential for discriminatory profiling of particular communities.
Judicial Developments
The Aarushi-Hemraj murder case of 2008, which resulted in conviction of the parents in 2013 and their acquittal by the Allahabad High Court in 2017, became a landmark in public and judicial consciousness about the reliability of forensic evidence. The case involved contested CBI investigation, allegations of evidence tampering, competing forensic narratives, and expert witnesses whose credibility was challenged on multiple grounds. The Allahabad High Court’s acquittal was based substantially on the finding that the prosecution had not proven its case beyond reasonable doubt, partly because of the inadequacy and inconsistency of the forensic evidence presented. The case generated significant discussion about the standards that forensic evidence in Indian courts must meet, and about the institutional conditions that produce reliable forensic work.
Several High Court judgments have noted with concern the delays in forensic science laboratory reports and the impact of those delays on criminal trials. The Allahabad High Court, in multiple criminal appeals, has observed that FSL reports received years after the investigation are of limited utility and that the condition of biological samples stored without adequate protocols means that the reliability of analysis conducted on such samples is questionable. These are not isolated observations; they reflect a systemic problem with the infrastructure of forensic science in India.
The Supreme Court, in Selvi v. State of Karnataka (2010), addressed the admissibility of narco-analysis, brain mapping, and polygraph tests in criminal investigations. The Court held that compelling a person to undergo such tests violates the right against self-incrimination under Article 20(3) and the right to life and personal liberty under Article 21. The judgment drew on scientific literature to question the reliability of these techniques, demonstrating that courts can and should engage with the scientific basis of expert evidence rather than simply deferring to the ipse dixit of the expert. This approach to critical evaluation of forensic methodology has not, however, been applied consistently across all forms of scientific evidence.
Digital forensics cases have produced a growing body of jurisprudence on chain of custody requirements. The Bombay High Court and the Delhi High Court have in several cases excluded or discounted digital evidence where the prosecution could not demonstrate an unbroken chain of custody from seizure of the device to presentation of the analysis, or where the investigating officer was unable to explain the specific extraction and analysis methodology used. These judgments represent an important development in the courts’ engagement with the technical requirements of digital evidence but remain insufficient to establish a general standard.
Contemporary Issues and Analysis
The chain of custody problem is pervasive in Indian forensic evidence. For biological samples collected at crime scenes, the path from collection through transportation to the FSL, storage within the FSL, and analysis must be documented at each step. In practice, documentation is often inadequate: samples may be transported without refrigeration, stored in suboptimal conditions, and the specific analyst who conducted the testing may not be available to testify because of transfers or retirement. These practical failures create vulnerabilities that defence counsel can exploit and that in some cases genuinely compromise the reliability of the evidence.
India’s Forensic Science Laboratories operate under varying degrees of state capacity and oversight. Some states have well-equipped FSLs with specialised units for DNA profiling, digital forensics, toxicology, and ballistics. Others have facilities that are significantly underfunded and understaffed, with backlogs of samples waiting for analysis that run into tens of thousands. The NCRB’s data on crime records does not comprehensively capture FSL capacity and performance, making systematic national assessment difficult.
The expert witness credibility problem is both institutional and procedural. Institutionally, FSL scientists who testify as expert witnesses are government employees who are part of the investigative apparatus. This creates at least the appearance of institutional partiality, as the expert who analyzes the evidence is employed by the same state that prosecutes the accused. The adversarial system addresses this through cross-examination, but cross-examination of a scientific witness is effective only when the cross-examining lawyer has sufficient scientific literacy to identify the relevant questions. In most criminal trials in India, defence counsel does not have access to independent forensic experts who can review the prosecution’s analysis and identify flaws.
The Daubert standard, articulated by the United States Supreme Court in Daubert v. Merrell Dow Pharmaceuticals (1993), requires federal courts to act as gatekeepers of scientific evidence, evaluating whether the expert’s methodology is based on sufficient facts, is the product of reliable principles and methods, and has been reliably applied to the facts of the case. The earlier Frye standard required general acceptance in the relevant scientific community. India’s approach, based on the “specially skilled” person test in Section 45 BSA, does not incorporate either of these more demanding standards. The court’s role in evaluating the reliability of the methodology, as opposed to merely the qualifications of the expert, is not clearly established.
Digital forensics presents particular challenges. The extraction of data from mobile phones, computers, and cloud services using specialised software tools produces outputs that are dependent on the specific tool used, its version, and the parameters of the extraction. Different tools may produce different results from the same device. The absence of accreditation standards for the specific tools and methodologies used in digital forensics means that courts cannot evaluate the reliability of the process without expert guidance that is frequently unavailable to them.
Comparative and International Perspective
The United States has a national forensic science infrastructure that, while imperfect, includes the FBI Laboratory, National Institute of Standards and Technology guidelines for forensic science, and academic institutions that independently study and critique forensic methods. The 2009 National Academy of Sciences report “Strengthening Forensic Science in the United States” was a landmark critical assessment that identified significant weaknesses in multiple forensic disciplines and recommended substantial reform. The subsequent establishment of the National Commission on Forensic Science reflected a commitment to improving standards through a multi-stakeholder process. The UK Forensic Science Regulator, established in 2008 and given statutory powers through the Forensic Science Regulator Act 2021, has authority to set quality standards for forensic science providers and to investigate quality issues. Accreditation against international quality management standards is mandatory for forensic science providers supplying evidence to courts.
Germany’s approach to forensic science is characterised by strong accreditation requirements, institutional separation between investigative and analytical functions, and the routine appointment of court-appointed neutral experts in addition to party experts, which reduces the adversarial quality of forensic evidence presentation and focuses judicial attention on scientific consensus rather than partisan disagreement.
Practical and Policy Implications
The consequences of inadequate forensic evidence standards are bidirectional. Where forensic evidence that is unreliable or inadequately analysed supports a conviction, an innocent person may be wrongfully convicted. Where forensic evidence that is reliable is rendered inadmissible or discounted because of chain of custody failures or inadequate expert testimony, a guilty person may be acquitted. Both types of error are serious, and both are produced by the same institutional failures.
The National Forensic Sciences University, established under the National Forensic Sciences University Act 2020, represents a significant investment in the institutional infrastructure of forensic science in India. Its mandate includes developing standardised training programmes, conducting research into forensic methods, and providing expertise to criminal justice agencies. The University’s potential contribution to improved forensic standards is substantial, but it requires integration with the FSL system and the criminal courts to produce the changes that matter at the point where evidence is collected, analysed, and presented.
Suggestions and Reforms
Parliament should expedite the passage of the DNA Technology (Use and Application) Regulation Bill through the Rajya Sabha, with amendments to address the legitimate privacy concerns that have been raised. A regulated DNA database, subject to judicial oversight and stringent access controls, is a necessary component of a modern forensic science infrastructure. The privacy risk of a DNA database can be managed through clear statutory limitations on data retention, access, and use; it should not be a reason to forgo the substantial benefits that DNA profiling brings to serious crime investigation.
A mandatory accreditation requirement for forensic science laboratories should be established, with the NABL (National Accreditation Board for Testing and Calibration Laboratories) or a specialist forensic accreditation body as the accrediting authority. The requirement should apply to all FSLs submitting evidence to criminal courts. Accreditation should cover quality management systems, proficiency testing, and validation of specific methods.
The CERT-In guidelines on digital forensics should be developed into a comprehensive national standard for digital evidence collection, preservation, and analysis, with mandatory compliance for investigative agencies. The standard should address chain of custody for digital devices, extraction methodology, hash verification, and report format.
Courts should be empowered to appoint neutral court experts in cases involving complex scientific evidence, supplementing the testimony of party experts and providing an independent assessment to assist the judge in evaluating technical disputes. This reform would reduce the adversarial dimension of expert testimony and improve the quality of judicial engagement with scientific evidence.
Conclusion
India’s forensic science framework is at a critical moment of transition. The NFSU Act, the pending DNA Bill, and the digital forensics guidelines represent the pieces of a reform agenda that, if assembled coherently, could substantially improve the reliability and integrity of scientific evidence in Indian courts. The missing element is the institutional coordination and the political will to make accreditation mandatory, to fund laboratory infrastructure adequately, and to bring the standards of expert evidence presentation into alignment with what modern forensic science requires. The Aarushi case and others like it demonstrate that the consequences of inadequate forensic standards are not merely technical; they are human, deeply so, and they undermine the legitimacy of criminal justice outcomes in ways that no subsequent reform can fully repair.
