Why in news?

In Kattavellai @ Devakar v. State of Tamil Nadu, the Supreme Court mandated strict protocols for DNA evidence in criminal cases.

It directed all State DGPs to prepare Chain of Custody Register forms and related documentation, and circulate them to all districts with clear instructions to ensure the integrity and reliability of DNA samples.

What’s in Today’s Article?

• Need for Uniform DNA Handling Guidelines
• Supreme Court’s Guidelines on Handling DNA Evidence
• Supreme Court’s Rulings on DNA Evidence
• Importance of DNA Evidence in Criminal Cases
• Conclusion

Need for Uniform DNA Handling Guidelines

• In the Kattavellai @ Devakar case, involving rape, murder, and robbery, the Supreme Court found serious lapses, including unexplained delays in sending vaginal swab samples to the Forensic Science Laboratory and failure to establish a clear chain of custody.
• These gaps raised the possibility of contamination. The Court noted that while some bodies had issued guidelines, there was neither uniformity nor a common procedure across states.
• Given that ‘Police’ and ‘Public Order’ fall under the State List, the Court still found it essential to issue uniform directions to ensure consistency and reliability in DNA evidence handling nationwide.

Supreme Court’s Guidelines on Handling DNA Evidence

• The Supreme Court laid down four key guidelines to ensure the integrity of DNA evidence in criminal cases.
• First, DNA samples must be collected with due care, properly packaged with FIR details, case particulars, and duly documented with signatures of the medical professional, investigating officer, and independent witnesses.
• Second, the investigating officer must transport the samples to the concerned police station or hospital and ensure they reach the Forensic Science Laboratory within 48 hours; any delay must be explained with preservation measures taken.
• Third, once stored, samples cannot be opened, altered, or resealed without trial court authorisation.
• Finally, a Chain of Custody Register must be maintained from collection until conviction or acquittal, appended to the trial record, with the investigating officer accountable for any lapses.

Supreme Court’s Rulings on DNA Evidence

• The Supreme Court has consistently stressed that DNA evidence, though powerful, must meet strict standards of collection and handling.
• In Anil v. State of Maharashtra (2014), it upheld DNA profiling as valid and reliable, provided laboratory procedures maintain quality control.
• In Manoj v. State of Madhya Pradesh (2022), a DNA report was rejected due to contamination risk from recovery in an open area and insufficient, degraded blood samples.
• Similarly, in Rahul v. State of Delhi (2022), DNA evidence was discarded because it remained in police custody for two months, raising suspicion of tampering.
• In the Devakar case, the Court emphasised that quality control outside laboratories — in collection, sealing, and timely dispatch — is as critical as lab procedure.
• Thus, both investigating agencies and forensic experts must ensure rigorous safeguards to maintain credibility of DNA evidence.

Importance of DNA Evidence in Criminal Cases

• DNA, derived from biological materials like blood, bone, semen, saliva, hair, or skin, helps establish whether a crime scene sample matches a suspect.
• While such matches can strongly indicate common biological origin, the Supreme Court in the Devakar case clarified that DNA is only opinion evidence under Section 45 of the Evidence Act (now Section 39 of the Bharatiya Sakshya Adhiniyam, 2023).
• Its probative value depends on the circumstances of each case. Thus, DNA evidence is significant but not conclusive, and must be scientifically validated and legally established to hold weight in criminal proceedings.

Conclusion

The Supreme Court’s guidelines on DNA evidence aim to ensure reliability, prevent contamination, and strengthen criminal justice. Their success depends on consistent enforcement by police and forensic agencies.