Accreditation and Quality as a Legal Requirement

ISO/IEC 17025 sets out what a competent laboratory must have in place. The 2017 revision reorganised the standard around five main sections: general requirements (impartiality and confidentiality), structural requirements (legal identity and scope), resource requirements (personnel, equipment, and reference standards), process requirements (method validation, sampling, and handling of items), and management system requirements (document control, internal audit, and corrective action). For forensic work, the process requirements section is the most operationally significant: a laboratory must demonstrate that each analytical method it uses has been validated, that equipment is calibrated and maintained, and that results can be traced back to reference standards.

Method validation under ISO/IEC 17025 means producing documented evidence that a method measures what it claims to measure, with a known and acceptable error rate, under specified conditions. This is directly connected to the Daubert reliability inquiry in US courts and to equivalent reliability assessments in other jurisdictions. An accredited laboratory has already produced that documentation; an unaccredited one may not have done so at all, or may have done so internally without independent review.

Accreditation also requires a scope document: the laboratory's accreditation certificate lists precisely which tests, methods, and matrices are covered. A laboratory accredited for firearms examination is not automatically accredited for toxicology. This scope specificity matters legally because a result from a test outside the accreditation scope lacks the quality assurance even if the laboratory holds a certificate in a different area.

US federal courts assess forensic evidence under Federal Rule of Evidence 702 as interpreted by Daubert v. Merrell Dow Pharmaceuticals (1993) and its progeny. The Daubert factors include whether the technique has been tested, has a known error rate, has been subjected to peer review, and is generally accepted. Accreditation under ISO/IEC 17025 is not a Daubert factor in terms, but it is relevant evidence that a laboratory has validated its methods and maintains known error rates.

The 2009 National Academy of Sciences report Strengthening Forensic Science in the United States found that most forensic disciplines outside DNA lacked adequate validation and quality controls. The 2016 President's Council of Advisors on Science and Technology (PCAST) report went further, finding that several pattern-matching disciplines (including bite mark analysis and hair microscopy) lacked foundational validity entirely. Both reports recommended mandatory accreditation and proficiency testing for all forensic laboratories. Federal legislation implementing mandatory accreditation has been proposed in multiple sessions of Congress but not enacted at the federal level. Several US states have enacted their own accreditation requirements for public crime laboratories.

In practice, federal prosecutors and most state prosecutors require that forensic work be produced by accredited laboratories. The standard contract terms for laboratory services used by federal agencies specify ISO/IEC 17025 accreditation. This means that even without a comprehensive federal statute, accreditation has become a de facto requirement for work that will be used in federal prosecutions.

England and Wales moved further than any other common law jurisdiction by creating a statutory regulator with enforcement powers. The Forensic Science Regulator Act 2021 placed the Forensic Science Regulator on a statutory footing for the first time. Before the Act, the FSR role existed but was advisory. The Act gives the Regulator power to issue a mandatory Code of Conduct, investigate complaints, and require non-compliant providers to cease supplying forensic services to the criminal justice system.

The FSR Code of Conduct, updated following the Act, requires that forensic activities supplied into the criminal justice system be conducted in accordance with ISO/IEC 17025 as assessed by UKAS. The requirement covers public police laboratories, private forensic providers, in-house police digital evidence units, and defence experts who supply reports to court. The Regulator publishes a register of compliant providers, and courts are expected to give reduced weight to evidence from providers not on the register.

The 2021 Act was partly a response to the closure of the Forensic Science Service (FSS) in 2012, which fragmented the market among smaller private providers with uneven quality controls. Between 2012 and the Act, defence counsel successfully challenged several convictions on the basis that private laboratory work used in the original prosecution lacked adequate quality assurance. The Act made recurring accreditation failure a legal problem for the provider, not merely a professional embarrassment.

India does not yet have a statute making laboratory accreditation a precondition for admissibility. The Bharatiya Sakshya Adhiniyam 2023 (BSA), which replaced the Indian Evidence Act 1872, retains the court's broad discretion to admit and weigh scientific evidence. Section 45 BSA preserves the rule that court opinions of experts on questions of science are relevant, without specifying quality requirements for the expert's laboratory. The Bharatiya Nagarik Suraksha Sanhita 2023 (BNSS), which replaced the Code of Criminal Procedure, similarly does not specify accreditation requirements for forensic laboratories.

NABL accreditation under ISO/IEC 17025 is available to Indian forensic science laboratories and is increasingly expected by both prosecution and defence. Several Central Forensic Science Laboratories (CFSLs) hold NABL accreditation. State FSLs vary considerably: some are accredited, others are not. High courts in India have in several cases noted the absence of quality documentation as grounds for reduced weight, though not for automatic exclusion. This judicial practice, without a statutory basis, creates pressure toward accreditation without mandating it.

The Digital Personal Data Protection Act 2023 in India does not directly affect forensic evidence admissibility, but it has introduced requirements for data handling that intersect with digital forensic laboratory practices, particularly around chain-of-custody records for electronic evidence. Laboratories processing digital evidence must now consider both forensic quality standards and data protection obligations when designing their procedures.

Courts across jurisdictions have developed a consistent analytical structure when evaluating unaccredited forensic work. The first question is whether accreditation is required by statute or regulation: if it is, the court may exclude the evidence or require a remand to an accredited laboratory. If no statutory requirement exists, the court moves to the second question: does the absence of accreditation affect reliability?

Under Daubert in the US, an unaccredited result is not automatically unreliable. The proponent must still demonstrate reliability through the Daubert factors. But the absence of accreditation means that validation records, error rates, and quality controls must be established through testimony and documentation at the hearing, rather than being presumed from accreditation status. This increases the cost and complexity of admission and creates more opportunities for challenge.

A recurring pattern in post-conviction review cases is that unaccredited work contributed to wrongful convictions not because the results were necessarily wrong, but because the absence of quality controls meant that errors were not caught and documented. The West Midlands Police Forensic Science Laboratory, the FBI hair microscopy unit, and several private DNA laboratories have all featured in exonerations where the common thread was inadequate quality management rather than deliberate fraud.

Accreditation certificates are scope-specific: they cover named methods on named sample types. A laboratory may be accredited for blood alcohol analysis by gas chromatography but not for the same analysis by a different method. It may be accredited for DNA profiling from reference samples but not from degraded samples. Using an accredited laboratory does not guarantee that the specific analysis conducted falls within the accreditation scope.

Defence counsel in technically complex cases routinely request the laboratory's schedule of accreditation to check whether the specific method and matrix used in the case falls within scope. Finding that a result was produced by a method not covered by the accreditation certificate is functionally equivalent to finding that the result was produced by an unaccredited laboratory for that purpose. Courts have accepted this argument in several jurisdictions and treated out-of-scope results as carrying reduced weight.

A related issue is gap disciplines: some forensic specialties lack validated methods at all, and accreditation bodies cannot certify a laboratory to perform a method that has not been validated. Bite mark analysis, voice comparison, and handwriting examination are three disciplines where foundational validity has been contested in the academic and legal literature. For these disciplines, accreditation provides less assurance because the benchmark the accreditation tests against may itself be disputed. The appropriate response is to address the foundational validity issue through the admissibility standard, not to treat accreditation as a substitute for that analysis. For more on how courts assess foundational validity, see The Daubert Standard and Its Progeny and Admissibility Standards Around the World.