7 Key Rules for Biometric Evidence Legal Admissibility in 2025

In the modern Indian legal landscape, the intersection of technology and law is more pronounced than ever. Biometric evidence—such as fingerprints, DNA, and iris scans—has become a cornerstone of criminal and civil investigations across Delhi NCR. However, its presentation in court is not a simple matter of fact. The admissibility of such sophisticated forensic evidence is governed by stringent legal principles, procedural safeguards, and constitutional boundaries. As a leading law firm with over 40 years of combined experience, The Kanoon Advisors has navigated countless cases where the validity of biometric evidence was the pivotal point of the trial.

This comprehensive guide delves into the legal framework governing biometric evidence in India, updated for 2025. We will explore the key statutes, landmark judicial precedents from the Supreme Court and High Courts, and the procedural requirements that determine whether this form of evidence can be legally considered in a courtroom. Understanding these nuances is critical for anyone facing legal proceedings where forensic science plays a role, as the improper handling or interpretation of such evidence can lead to wrongful convictions or the dismissal of a valid claim.

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Table of Contents

• The Legal Framework for Biometric Evidence in India
• The Test of Admissibility: How Courts Scrutinize Forensic Evidence
• Types of Biometric Evidence and Their Legal Standing
• Challenges and Defences in Biometric Evidence Cases
• Why Choose The Kanoon Advisors for Your Case
• Frequently Asked Questions About Biometric Evidence
• Conclusion: Navigating the Complexities of Forensic Evidence

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The Legal Framework for Biometric Evidence in India

The admissibility of any evidence in an Indian court is primarily governed by the Indian Evidence Act, 1872. However, for scientific and biometric evidence, several other statutes and constitutional principles come into play, creating a multi-layered legal framework. Understanding this foundation is the first step in assessing the strength or weakness of a case involving forensics.

What is the statutory basis for admitting biometric evidence?

The legal basis for biometric evidence is not found in a single law but is spread across several key pieces of legislation. At The Kanoon Advisors, our approach begins with a thorough analysis of these statutes in the context of our client’s case.

• The Indian Evidence Act, 1872: This is the parent legislation. Section 45 is paramount, as it allows the court to rely on the opinions of experts in fields like science, art, or handwriting identification. Biometric evidence falls under this category, requiring a forensic expert to depose and explain the findings. Section 9 further establishes the relevance of facts that support or rebut an inference, which is where a DNA match or fingerprint match becomes legally significant.
• The Code of Criminal Procedure, 1973 (CrPC): Sections 53 and 53A of the CrPC empower a registered medical practitioner, at the request of a police officer, to examine an arrested person and collect samples like blood, semen, and hair for DNA profiling, especially in cases of sexual assault.
• The Criminal Procedure (Identification) Act, 2022: This new act has significantly expanded the powers of law enforcement agencies to collect, store, and analyse biometric data. It replaced the older Identification of Prisoners Act, 1920. The Act allows police to collect “measurements,” which include fingerprints, palm-print impressions, footprints, iris and retina scans, and biological samples. This expansion has raised constitutional questions, which are currently under judicial scrutiny.

How does the Constitution of India impact biometric evidence collection?

While statutes provide the power to collect evidence, the Constitution of India places crucial limitations to protect individual liberties. Any collection of biometric data must withstand the test of constitutional validity, primarily concerning two fundamental rights:

• Article 20(3) – Right against Self-Incrimination: This article states that no person accused of an offence shall be compelled to be a witness against himself. For years, the debate was whether giving a fingerprint or blood sample amounted to “being a witness.” The Supreme Court, in State of Bombay vs. Kathi Kalu Oghad, clarified that providing such samples is not the same as testimonial compulsion. Therefore, the collection of biometric data, when done under legal authority, does not violate Article 20(3).
• Article 21 – Right to Life and Personal Liberty (including Right to Privacy): In the landmark case of Justice K.S. Puttaswamy (Retd.) vs. Union of India, the Supreme Court declared the Right to Privacy a fundamental right. Any state intrusion, including the collection of biometric data, must be justified. The state must prove that there is a legitimate aim, that the measure is proportional to the aim, and that there is a legal framework to prevent misuse. This judgment is the primary lens through which the validity of laws like the 2022 Act is now examined. An authoritative summary can be found on the Supreme Court of India website.

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The Test of Admissibility: How Courts Scrutinize Forensic Evidence

Simply collecting biometric evidence is not enough; it must pass a rigorous test of admissibility in court. The burden of proof lies on the prosecution to establish its credibility beyond a reasonable doubt. At our law firm, we have found that focusing on procedural lapses is often the most effective strategy in challenging questionable forensic evidence. According to court statistics, a significant percentage of acquittals in cases relying on forensics are due to a broken chain of custody or improper expert testimony.

Why is the ‘Chain of Custody’ non-negotiable?

The chain of custody refers to the chronological documentation or paper trail, showing the seizure, custody, control, transfer, analysis, and disposition of evidence. A single unexplained gap in this chain can render the evidence inadmissible. The court needs assurance that the evidence presented is the exact same evidence collected from the scene or person, and that it has not been tampered with or contaminated.

Step-by-Step Process for a Valid Chain of Custody

1. Proper Collection and Sealing: The evidence must be collected by a trained officer or forensic expert. It must be properly sealed in a tamper-proof container at the spot, and the seal must be signed by the collecting officer and preferably by independent witnesses.
2. Documentation and Labeling: A memo (seizure memo) must be prepared detailing the date, time, location, nature of the evidence, and the names of the witnesses. The sealed package must be labeled accurately.
3. Secure Transportation and Storage: The evidence must be transported securely to the police station’s ‘malkhana’ (evidence room) and then to the Forensic Science Laboratory (FSL). Every person handling the evidence must be documented.
4. Analysis at the FSL: The FSL must confirm that it received the seal intact before opening the sample for analysis. The report prepared by the expert must detail the condition of the sample upon receipt.

An experienced criminal lawyer will meticulously cross-examine every witness involved in this chain—from the constable who collected the sample to the expert who analysed it—to find inconsistencies.

What is the role of an expert witness under Section 45?

Biometric evidence is incomprehensible to a layperson. Therefore, Section 45 of the Indian Evidence Act allows the opinion of a skilled expert to be considered a relevant fact. However, the expert’s report is not automatically accepted. The expert must be prepared to defend their findings in court under cross-examination. The court evaluates not just the conclusion of the report, but also the methodology, the scientific principles applied, and the expert’s own qualifications and credibility. A mere report without the expert’s testimony is often considered weak evidence.

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Types of Biometric Evidence and Their Legal Standing

Different types of biometric evidence carry different weight in court. Their probative value—the ability of the evidence to prove something material to the case—varies based on the reliability of the science behind them. Courts in Delhi NCR, like elsewhere in India, are cautious and assess each type on its own merits.

Fingerprint Evidence

Fingerprint evidence has been used for over a century and is considered to have high probative value due to the unique nature of friction ridge patterns. The opinion of a fingerprint expert is admissible under Section 45. However, it’s not infallible. Challenges can be made based on the quality of the latent print recovered from the crime scene (e.g., if it was smudged or partial) or the methodology used for comparison.

DNA Evidence

DNA (Deoxyribonucleic Acid) profiling is considered the gold standard in forensic science. A DNA match can provide powerful corroborative evidence linking a suspect to a crime scene or a victim. The Law Commission of India has repeatedly emphasized its importance in the criminal justice system. However, its admissibility is contingent on a perfect chain of custody to prevent contamination, and the statistical probability of a random match must be clearly explained to the court by the DNA expert.

Newer Forms: Facial Recognition, Voice Spectrography, and Iris Scans

These emerging technologies are viewed with greater caution by the courts. The science behind voice spectrography, for instance, has been debated, and courts often rule that it cannot be the sole basis for conviction. Facial recognition from CCTV footage is often treated as supportive evidence, but its accuracy can be challenged based on factors like video quality, lighting, and angles. The legal framework is still evolving to keep pace with these technologies.

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Challenges and Defences in Biometric Evidence Cases

The presence of biometric evidence against an accused does not automatically mean a conviction. A skilled legal defence involves a multi-pronged strategy to challenge the evidence at every stage. With decades of litigation experience in the district courts of Delhi NCR, as well as the High Courts and Supreme Court, our team at The Kanoon Advisors specializes in scrutinizing forensic evidence to protect our clients’ rights.

How can biometric evidence be challenged in court?

Even the most scientific-looking evidence can have procedural or substantive flaws. Our legal team focuses on several key areas when building a defence:

• Violation of Procedure: Was the sample collected without legal authority or consent where required? Was the procedure laid down in the CrPC or the Identification Act followed correctly?
• Breaking the Chain of Custody: As discussed, any gap or inconsistency in the evidence trail is a strong ground for challenge. We meticulously examine all documentation, including seizure memos, road certificates, and FSL receipts.
• Contamination of Evidence: DNA and other biological samples are highly susceptible to contamination. We investigate the conditions under which the evidence was collected, stored, and analysed.
• Challenging the Expert Witness: An expert’s qualifications, experience, and the reliability of their testing methods can be questioned during cross-examination. We also explore whether their opinion is based on sound scientific principles or is merely a subjective conclusion.
• Lack of Corroboration: The Supreme Court has held in multiple judgments that it is generally unsafe to convict a person solely on the basis of expert opinion without independent corroboration. We argue for the need for other supporting evidence to connect the accused to the crime.

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Frequently Asked Questions About Biometric Evidence

Q1: Is it mandatory to provide biometric samples to the police in India?

Yes, under the Criminal Procedure (Identification) Act, 2022, a person who is arrested, convicted, or under preventive detention can be compelled to provide “measurements,” including biometric samples. Refusal can lead to legal consequences. However, the collection must follow the prescribed legal procedure.

Q2: What is the difference between admissibility and reliability of biometric evidence?

Admissibility is a legal question: does the evidence meet the legal requirements to be presented in court? This involves checking the chain of custody and procedural compliance. Reliability is a factual question for the judge: how much weight or importance should be given to the evidence? Evidence can be admissible but found unreliable if, for example, the sample was of poor quality.

Q3: Can a case be won or lost solely on biometric evidence?

While strong biometric evidence like a DNA match can be very persuasive, courts are generally cautious about convicting someone based solely on it. The Supreme Court has often emphasized the need for corroborative evidence that independently points towards the guilt of the accused. It is a crucial piece of the puzzle, but rarely the entire picture.

Q4: How has the Criminal Procedure (Identification) Act, 2022 changed the rules?

The 2022 Act has significantly broadened the scope of data that can be collected, the list of persons from whom it can be collected, and the duration for which it can be stored (up to 75 years). It allows the collection of behavioural attributes and biological samples beyond just blood and hair. Its constitutional validity is still being debated in courts.

Q5: What should I do if I believe biometric evidence against me is false or tampered?

If you suspect that biometric evidence is fabricated or compromised, it is imperative to contact an experienced criminal defence lawyer immediately. Do not wait for the trial. Your lawyer can file applications to have the sample re-tested by an independent laboratory, challenge the police procedure, and prepare to cross-examine the witnesses involved in the evidence handling chain.

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Conclusion: Navigating the Complexities of Forensic Evidence

The legal landscape surrounding biometric evidence in India is both complex and dynamic. While advancements in forensic science offer powerful tools for investigation, their use is rightfully tempered by strict legal standards and constitutional safeguards to protect citizens from error and misuse. The admissibility of such evidence is never guaranteed; it depends entirely on the meticulous adherence to legal procedure, the integrity of the chain of custody, and the scrutiny it can withstand in a court of law.

Whether you are facing charges based on forensic evidence or seeking to use it to support your claim, understanding your rights and the legal requirements is paramount. An oversight in procedure can be the difference between a successful outcome and a miscarriage of justice. It is essential to have legal representation that not only understands the law but also has the experience to challenge scientific evidence effectively.