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Apex court lays down nationwide norms on DNA evidence handling
The court set aside the conviction of Kattavellai, finding that the prosecution’s case, which was anchored almost entirely on DNA evidence, was marred by serious procedural deficiencies
New Delhi The Supreme Court on Tuesday issued binding nationwide guidelines to regulate the collection, preservation, and processing of DNA and other biological materials, declaring that the lack of standardised procedures has grave implications for fair trials and justice delivery.
The decision by a bench comprising Justices Vikram Nath, Sanjay Karol and Sandeep Mehta came while acquitting a man, who was on death row for the rape and murder of a couple in Tamil Nadu in 2011. The court set aside the conviction of Kattavellai, finding that the prosecution’s case, which was anchored almost entirely on DNA evidence, was marred by serious procedural deficiencies that rendered the scientific evidence unreliable.
“This lack of a common procedure to be followed is concerning...The aspects in which we find there to be errors committed regularly are in fact procedural aspects which aid the sanctity of the evidence,” noted the court, adding that differing regional practices cannot apply to sensitive evidence like DNA, which must be maintained in “pristine condition”.
Recognising the urgent need for consistency in how biological evidence is handled across the country, the top court underscored that the lack of a unified protocol had allowed critical lapses to creep into investigations. It noted that although various government bodies have issued manuals and standard operating procedures (SoPs) on handling forensic evidence, these remain largely advisory and are implemented unevenly across states. To address this, the court issued nationwide directions that are to be followed in all criminal cases involving DNA evidence.
The bench mandated that every DNA sample collected must be properly packaged and labelled with the FIR number, the applicable legal provisions, details of the investigating officer, the name of the police station and a serial number. This documentation must carry the signatures of the medical professional who assisted in the collection, investigating officer (IO), and, if possible, an independent witness. Even if no independent witness is available, the officer must record the efforts made to secure one and the reasons for their absence.
Further, it held that IO would bear responsibility for promptly transporting the DNA samples to the concerned forensic laboratory. The court directed that this must be done within 48 hours of collection to preserve the evidentiary value of the sample. If, due to unforeseen circumstances, this timeline cannot be met, the reasons for the delay must be recorded in the case diary, and the samples must be preserved according to the standards required for the particular type of biological material.
To guard against tampering, the court held that once DNA evidence is sealed, it must not be opened or resealed without the trial court’s express permission. This permission should be based on a medical expert’s assurance that such action will not compromise the integrity of the sample and that re-examination is essential for the proper conduct of the trial or investigation.
Lastly, the bench made it mandatory to maintain a chain of custody register for every piece of biological evidence, from the moment it is collected until the trial concludes. This register must document every transfer of the sample, along with the reasons for the movement, and must be counter-signed at every stage. The register will form part of the trial court record, and any failure to maintain it will require a written explanation from the investigating officer.
By making these directives binding, the Supreme Court sought to remove discretion and inconsistency from procedures involving one of the most sensitive forms of scientific evidence in criminal law. It also instructed the directors general of Police of all states to prepare standardised forms for such documentation and circulate them to every district, and requested state police academies to initiate training for officers to ensure full compliance.
The court further called the conviction a “worrying feature”, stating that the prosecution’s case “had no legs to stand on whatsoever” and yet the appellant had remained in custody for years, facing the death penalty.
While stopping short of ordering compensation, the bench referred to practices in foreign jurisdictions like the United States, where wrongful incarceration following eventual acquittal leads to statutory or judicial compensation.
“We may only see that in case such an approach is adopted, we would not be breaking new ground but only affirming our commitment to the constitutional guarantee of Right to Life under Article 21… Well, it is for the legislature to consider this aspect,” said the court.
