Why in News: The Supreme Court in Kattavellai Devakar v. State of Tamil Nadu (2025) issued uniform guidelines for handling DNA samples in criminal cases, after finding lapses like delayed dispatch to FSL and broken chain of custody, which raised concerns of contamination and reliability of evidence.
Reasons for SC Intervention
- Case-specific lapse: In Devakar, vaginal swab samples were delayed in being sent to the FSL and the chain of custody was not established.
- Possibility of contamination: Unexplained delays and improper handling could compromise results.
- Lack of uniformity: Different states followed different practices; no common procedure existed.
- Fundamental rights concern: Wrongful convictions due to mishandled evidence violate Article 21 (fair trial).
Lapses Uncovered
- Unexplained delay in dispatching samples.
- Missing or incomplete chain of custody records.
- Improper sealing, storage, and handling.
- Absence of accountability on investigating officers.
Court’s View on DNA Reliability (Past Rulings)
Anil v. State of Maharashtra (2014): DNA is valid & reliable if quality control maintained in labs.
Manoj v. State of MP (2022): DNA rejected due to contamination risk from open area recovery.
Rahul v. State of Delhi (2022): DNA discarded as samples stayed in police custody for two months.
Court stressed both inside-lab and outside-lab safeguards.
New Guidelines (2025)
- Proper documentation: FIR details, sealing, signatures of medical officer, IO, witnesses.
- Timely transport: IO responsible; samples to FSL within 48 hours.
- Storage protocol: No opening/resealing without trial court order.
- Chain of Custody Register: Maintained till conviction/acquittal.
Is DNA Alone Enough to Convict?
- DNA is opinion evidence under Section 45, Evidence Act (now Sec. 39, Bharatiya Sakshya Adhiniyam).
- Not substantive evidence; probative value varies case to case.
- Must be corroborated with other evidence for conviction.
Significance
- Strengthens scientific integrity of investigations.
- Balances technological advances with constitutional safeguards.
- Establishes uniform national standard despite policing being a State subject.
- Reinforces that DNA must be corroborated, not used in isolation.
Conclusion
The Supreme Court’s guidelines aim to standardise procedures, minimise contamination risks, and enhance the evidentiary value of DNA in criminal trials. While DNA is a vital forensic tool, it cannot stand alone as the sole basis of conviction without corroborative legal and factual evidence.
UPSC Relevance
GS-II (Polity & Governance): Role of Supreme Court in protecting fundamental rights, judicial intervention in fair trial and criminal justice.
Mains Practice Question
Q.“DNA evidence is a powerful investigative tool but not infallible. Critically examine the Supreme Court’s guidelines in Kattavellai @ Devakar v. State of Tamil Nadu (2025) in light of concerns over reliability, contamination, and fair trial rights.”(250 words)