The Statutory Role of the Forensic Laboratory

Forensic evidence enters court in two ways. The first is through a live expert who testifies under oath, is cross-examined, and whose qualifications and reasoning are tested in real time. The second is through a document, a certificate, a report, or a certified copy that the law allows to speak for itself. The second route is faster and cheaper, but it creates a constitutional and procedural question: what happens to the accused's right to challenge the person who made the finding?

Statutes address this by creating a framework. They specify which laboratories are authorised to produce reports that carry presumptive weight, what those reports must contain to be valid, and what mechanism the defence must use if it wants the examiner present. Without such a framework, courts would be forced to resolve these questions on a case-by-case basis through common law, which produces inconsistency. The statutory approach standardises the deal: the examiner's report is presumed authentic and reliable, and the defence can break that presumption only by taking a defined procedural step.

The practical scale of the problem is large. In a typical urban criminal court, a significant fraction of cases involves some forensic evidence: blood-alcohol readings from road traffic cases, controlled substance identifications from drug prosecutions, and digital extraction reports from phone seizures. If every such report required live testimony, the forensic scientist would spend most of the working week in court. Statutory shortcut rules allow laboratories to function as production facilities for documentary evidence, with court attendance reserved for contested cases.

India replaced the Code of Criminal Procedure 1973 with the Bharatiya Nagarik Suraksha Sanhita 2023 (BNSS) and the Indian Evidence Act 1872 with the Bharatiya Sakshya Adhiniyam 2023 (BSA), both operative from July 2024. The provisions governing forensic laboratory reports track the structure of the old law but introduce some changes in formulation.

Section 293 of the BNSS (equivalent to section 293 of the old CrPC) lists the categories of government scientific expert whose reports are admissible as evidence in any inquiry, trial, or other proceeding. The listed fields include chemical examiners, serologists, fingerprint experts, ballistic experts, handwriting and document examiners, and Central Forensic Science Laboratory experts. A report from any of these experts may be used as evidence. If the court or a party requires the expert to be examined as a witness, the court may summon and examine that person.

The BSA addresses the authenticity of documents through sections on presumptions. Section 79 of the BSA directs courts to presume that documents purporting to be official gazettes, court records, or certified copies of public documents are genuine. For forensic reports, the combined effect of the BNSS list and the BSA presumptions is that a properly signed and certified report from a listed government examiner enters the record without the examiner attending, and carries presumptive weight subject to the court's power to summon on application.

The BNSS also contains provisions on mandatory forensic examination for serious offences. Section 176(3) requires that where an offence punishable with seven years or more is alleged, the investigating officer must arrange for a forensic expert to visit the scene and collect evidence, if such facilities are available. This creates a statutory duty on the investigative side, separate from the admissibility rules, but it signals the legislature's intent that forensic evidence should be gathered as a matter of course in serious cases, not only when a party requests it.

Before 2009, many US states admitted forensic laboratory certificates as business records or public records without requiring the analyst's attendance. The US Supreme Court's decision in Melendez-Diaz v. Massachusetts, 557 U.S. 305 (2009), changed the constitutional baseline. The Court held that a forensic laboratory certificate, which in that case was an affidavit stating that substances seized from the defendant were cocaine, was a testimonial statement. Under Crawford v. Washington (2004), testimonial statements require the declarant to be available for cross-examination. The prosecution therefore could not simply tender the certificate; it had to produce the analyst or obtain the defendant's agreement to proceed without live testimony.

The immediate practical effect was significant. States that had relied on certificate-only practice had to adapt. The response was the notice-and-demand statute, now adopted in most US states in some form. Under a notice-and-demand scheme, the prosecution files a notice a set number of days before trial stating that it intends to use a forensic certificate. The defendant must then serve a written demand within a prescribed window, typically ten to twenty days, if they want the analyst to appear. If no demand is served, the right to confront is treated as waived and the certificate is admitted. The practical result is that in most cases the certificate still comes in without live testimony, because defence counsel either agrees with the findings or fails to object in time. The constitutional right survives; it is triggered by action, not automatically exercised.

Bullcoming v. New Mexico (2011) extended Melendez-Diaz: the prosecution could not satisfy the Confrontation Clause by calling a surrogate analyst who had not performed or observed the test and who simply read the absent analyst's report into the record. The person who actually conducted the examination must be the one available for cross-examination, or the defence must have had a prior opportunity to cross-examine the analyst who did. This matters in large laboratories where different staff members perform, review, and sign reports.

In England and Wales, the primary mechanism for getting forensic evidence before the court without live testimony is the section 9 statement under the Criminal Justice Act 1967. A written statement by a witness, signed with a declaration of truth, is admissible in criminal proceedings as if the witness had given the evidence orally, provided the other party receives a copy before the hearing and does not serve a counter-notice within the prescribed time requiring oral evidence. The system applies to any witness statement, but most routine forensic evidence takes this form.

The counter-notice period is typically set by the court timetable in the case management directions. In practice, defence solicitors review the forensic statements in the prosecution bundle and serve counter-notices only where the findings are genuinely contested or where the methodology needs to be tested. The system relies on professional judgment about when attendance is worth the cost and delay.

The Forensic Science Regulator Act 2021 added a structural quality layer. The Act gave the Forensic Science Regulator statutory powers to set Codes of Practice and Conduct for forensic science providers and to investigate failures to meet accreditation standards. If a laboratory is not accredited to the relevant ISO standard, or if it has failed to comply with the Regulator's Codes, a court may decline to admit its evidence or may give it less weight. The Act does not create new admissibility rules as such; it creates a quality infrastructure whose absence or breach can become relevant to admissibility under general principles.

A statutory shortcut is only useful if it can be set aside when the evidence genuinely needs to be tested. Each system provides a route to live examination, but the procedural and strategic considerations differ.

In India, the defence applies to the court, which exercises judicial discretion. The application is more likely to succeed where the report is central to the prosecution case, where the methodology is novel or contested, or where the defence has specific grounds to challenge the findings. The court is not obliged to grant every application; a vague or speculative challenge may be refused. This places a burden on the defence to identify a concrete reason for requiring attendance before the application is made.

In the US, once the defence serves a valid demand within the notice period, the analyst must appear or the certificate cannot be used. There is no judicial gate at the point of the demand. The analyst's attendance is mandatory. This gives the defence a stronger tool but also creates a strategic calculation: demanding every analyst in every case as a delay tactic is possible in theory, but courts have tools to manage it, and failure to make a specific demand means the right is lost.

In England and Wales, the counter-notice system is procedurally simple: the defence serves the notice, the witness attends, and there is no judicial gate on whether attendance is warranted. In practice, the court's case management powers can be used to challenge a counter-notice that appears to be served purely for delay where the findings are not genuinely in dispute. The Criminal Procedure Rules give judges broad powers to restrict actions that are disproportionate to the issues.

Cross-examination of a forensic examiner in any system tends to focus on three areas: the chain of custody from the scene to the laboratory, the methodology used and whether it meets the relevant scientific or legal standard, and the interpretation of the results. A forensic examiner who understands what a defence lawyer is likely to ask in these three areas is a more effective witness than one who knows only the technical detail of the analysis.

A statutory provision that makes a laboratory's report presumptively admissible assumes that the laboratory produces reliable results. If it does not, the statutory presumption can produce wrongful convictions. The response in several jurisdictions has been to link the statutory shortcut to a quality or accreditation requirement: only laboratories that meet prescribed standards may issue reports with statutory weight.

ISO/IEC 17025 is the international standard for testing and calibration laboratories. Accreditation bodies, such as UKAS in the UK, A2LA in the US, and the National Accreditation Board for Testing and Calibration Laboratories (NABL) in India, assess laboratories against this standard. An accredited laboratory has demonstrated competence in its scope of testing, maintains documented quality systems, and subjects itself to periodic reassessment. In England and Wales, the Forensic Science Regulator Act 2021 requires relevant forensic science providers to be accredited or to have a time-limited plan to achieve accreditation, backed by the Regulator's enforcement powers.

India's statutory list of approved government scientific experts under the BNSS does not currently require those experts to work in ISO 17025-accredited laboratories as a condition of the statutory provision applying. Accreditation is pursued by the Central Forensic Science Laboratory and state laboratories as a quality goal, but it is not written into the admissibility provision. This gap matters because a report from a listed expert is presumptively admissible regardless of whether the laboratory follows documented quality procedures. The defence can still challenge the methodology and results, but the challenge must be mounted case by case rather than relying on an accreditation gap.

The broader lesson across jurisdictions is that statutory evidentiary shortcuts work well when the laboratories behind them are consistently reliable, but they create systemic risk when laboratory quality is variable. Post-conviction reviews in the US and UK have repeatedly identified laboratory error, misconduct, and invalid methodology as contributing factors in wrongful convictions where the defendants did not challenge the certificates at trial. The legal framework shapes when challenge is available; the quality framework determines how often challenge is needed.