DNA Evidence in Criminal Cases

The Supreme Court has issued guidelines for the admission of DNA Evidence in Criminal Cases. Read here to learn more.

DNA (Deoxyribonucleic Acid) evidence has become a crucial tool in modern criminal justice systems for identifying perpetrators, exonerating the innocent, and ensuring reliable convictions.

However, its use in India has faced procedural and reliability challenges, leading to the Supreme Court’s recent intervention.

Table of Contents

Why Did the Supreme Court Intervene?

The Supreme Court, in Kattavellai @ Devakar v. State of Tamil Nadu (2025), stepped in after finding:

Breakdowns in Chain of Custody: DNA samples were not always collected, stored, or transferred following standard scientific protocols, risking contamination or tampering.
Documentation Lapses: Many police stations and forensic labs lacked proper registers or forms to record how samples were handled, who accessed them, and when.
Threat to Fair Trials: Inaccurate or compromised samples could lead to wrongful convictions or acquittals, undermining justice.

The Court held that DNA evidence, though highly reliable, is only as strong as the process used to collect and preserve it.

Supreme Court Guidelines on DNA Evidence in Criminal Cases

The SC issued comprehensive directions to standardise DNA sample collection and processing across the country:

Proper Documentation at Collection Stage:
- Each collection must be accompanied by a detailed record, mentioning FIR number, name and designation of Investigating Officer (IO), signatures of medical professionals collecting the sample, and independent witnesses.
- This ensures transparency and authenticity of evidence right from the start.
Authorisation Requirement:
- Samples must not be opened, resealed, or altered without prior permission from the trial court, ensuring no tampering during investigation.
Timely Transportation:
- IO must transport samples to the Forensic Science Laboratory (FSL) within 48 hours of collection to prevent degradation.
Chain of Custody Maintenance:
- A Chain of Custody Register must be maintained at every stage of collection, transfer, analysis, and until case closure.
- This register must be produced before the trial court as part of the case record.
Training and Awareness:
- Police, doctors, and forensic personnel must receive training on handling biological evidence, labelling, sealing, and storage protocols.

Key Issues Involved in DNA Evidence Management

While DNA evidence is highly reliable, its effective use faces multiple challenges:

Collection and Preservation Issues:
- Risk of contamination due to improper sealing or human handling.
- Degradation caused by exposure to heat, moisture, or delays in transportation.
- Insufficient quantity may render evidence unusable for retesting.
Analysis Issues:
- Human error in laboratory handling, interpretation, or labelling of samples.
- Absence of uniform forensic protocols across FSLs in India affects consistency.
Privacy Concerns:
- DNA databases raise concerns of mass surveillance, misuse of genetic data, and potential discrimination based on health or ancestry.
Interpretative Challenges:
- Overreliance on DNA can lead to wrongful convictions.
- Complex mixtures or partial DNA profiles are difficult to interpret and require expert testimony.

Past Judicial Stand on DNA Evidence

Indian courts have repeatedly emphasised the value of DNA evidence:

Kunhiraman v. Manoj (1991): First case where DNA technology was used in India, in a paternity dispute.
Sharda v. Dharmpal (2003): SC upheld DNA testing in civil/matrimonial disputes, ruling it does not violate Article 21 (personal liberty) or Article 20(3) (self-incrimination).
Santosh Kumar Singh v. State (2010): SC recognised DNA as the “most reliable form of evidence,” but only if a proper chain of custody is maintained.
Mukesh v. State (2017) (Nirbhaya Case): DNA profiling played a central role in upholding the conviction; the Court said it provided “virtually infallible evidence.”
Krishna Kumar Malik v. State of Haryana (2011): Stressed the need for scientific evidence, like DNA, to avoid reliance on weak oral testimony.
Rahul v. State of Delhi, MHA (2022): DNA evidence was rejected because the sample remained in police custody for two months, raising concerns of tampering.
Bharatiya Nagarik Suraksha Sanhita, 2023 (Section 51): Authorizes medical examination, including DNA profiling, of apprehended individuals by a registered medical practitioner.
Devakar Case (2025): Held that DNA evidence is opinion evidence under Section 39 of the Bharatiya Sakshya Adhiniyam, 2023. Its probative value depends on the facts of each case and must be corroborated with other evidence.

However, courts have also cautioned that DNA evidence should not be accepted blindly; contamination, human error, or mishandling can compromise its reliability.

Is DNA Alone Enough to Convict?

No. While DNA is considered highly reliable, courts have consistently ruled that it must be corroborated with other evidence, such as:

Witness testimony
Circumstantial evidence
Motive and opportunity
CCTV footage or electronic evidence

The SC has stated that DNA evidence alone cannot form the sole basis of conviction unless it rules out all reasonable doubt.

For example, a DNA match may prove presence at the scene but not necessarily guilt unless linked with other incriminating evidence.

Significance of the Guidelines

Strengthens Forensic Integrity: Reduces chances of sample contamination, tampering, or false implications.
Protects Rights of Accused: Ensures that no one is wrongfully convicted due to sloppy handling of scientific evidence.
Boosts Conviction Rates: Reliable forensic practices will help courts convict actual offenders with greater confidence.
Aligns India with Global Best Practices: Brings the Indian criminal justice system closer to international forensic standards.

Conclusion

The Supreme Court’s intervention in Kattavellai @ Devakar is a landmark step towards standardising forensic procedures in India.

While DNA evidence is a powerful tool, its reliability depends on robust collection, preservation, and documentation protocols.

These guidelines will help restore public trust, improve conviction rates, and ensure that justice is served both for victims and the accused.

DNA is not infallible: It is a powerful investigative tool, but cannot by itself conclusively establish guilt unless supported by corroborative evidence.
Due Process is Crucial: Proper chain of custody, documentation, and timely handling are key to making DNA evidence admissible.
Need for a Legal Framework: India still lacks a comprehensive DNA profiling law (the 2019 Bill is pending). A robust law is needed to balance forensic efficiency with privacy safeguards.

Related articles: