Relevance of DNA and Footprint Evidence in India: BSA & IEA

The Statutory Foundation for Expert Opinion

Before examining DNA and footprint evidence specifically, it is necessary to understand the statutory gateway through which all scientific evidence must pass. Section 45 of the Indian Evidence Act, 1872 — now reproduced as Section 39 of the BSA, 2023 — provides that when the Court has to form an opinion upon a point of science or art, or any other field, the opinions of persons specially skilled in that field are relevant facts, and such persons are called experts. The BSA has marginally expanded this by adding the words "or any other field," thereby future-proofing the provision to accommodate emerging sciences. Both sections share illustration (c), which makes the opinion of a forensic expert relevant when the question is whether a certain document was written by a particular person — the principle being extendable to all manner of identity questions in science and forensics.

It is essential to appreciate the fundamental principle behind Section 45/39: the law does not require courts to possess specialist knowledge. When the subject matter is beyond the ken of ordinary judicial experience — as DNA profiling and footprint identification unquestionably are — expert opinion becomes the bridge between raw scientific data and judicial understanding. As the Supreme Court observed in Ramesh Chandra Agarwal v Regency Hospital Ltd (AIR 2010 SC 806), the need to hear expert opinion is the first and foremost requirement when technical matters are in issue. However, the expert deposes; the Court decides. The expert furnishes the scientific criteria; the Judge applies them to the proved facts to form an independent conclusion.

DNA Evidence in Indian Courts

The Science and Its Legal Reception

Deoxyribonucleic acid, the genetic blueprint of every living organism, offers what the US Supreme Court described in District Attorney's Office v Osborne (2009) as an "unparalleled ability both to exonerate the wrongly convicted and to identify the guilty." The Indian courts have accepted this characterisation. In Kamti Devi v Poshi Ram (AIR 2001 SC 2226), the Supreme Court held that "the result of a genuine DNA test is said to be scientifically accurate." In Dipanwita Roy v Ronobroto Roy (2015 1 SCC 365), the Apex Court went further, declaring that "DNA testing is the most legitimate and scientifically perfect means" to establish biological identity. The Centre for Cellular and Molecular Biology (CCMB), Hyderabad, was prominently relied upon in Kunhiraman v Manoj (II 1991 DMC 499), where Dr. Lalji Singh testified that the accused shared all fifteen DNA bands with the child in question, placing the probability of their being unrelated at one in three hundred billion.

Under the Indian statutory framework, DNA evidence is primarily admitted as expert opinion under Section 45 IEA / Section 39 BSA. The Court does not directly read the DNA profile; it relies on the evidence of the expert who conducted the test and who testifies as to methodology, findings, and conclusions. Section 53 of the Code of Criminal Procedure, 1973 (now Section 51 of the BNSS, 2023), as amended in 2005, expressly permits a police officer to request a registered medical practitioner to examine an arrested person, including by "DNA profiling and such other tests which the registered medical practitioner thinks necessary." This amendment provided the much-needed statutory sanction for DNA evidence in criminal investigations that had previously been cobbled together through the inherent powers of courts.

Relevance as Corroborative Evidence

It is a settled proposition that DNA evidence, however powerful, does not stand alone. The science provides probabilistic rather than absolute identification in most forensic contexts. The English Court of Appeal in R v Alan James Doheny (1997 1 Cr App R 369) laid down the principle, adopted approvingly by Indian courts, that "the significance of the DNA evidence will depend critically upon what else is known about the suspect." The Court emphasised that "a comparatively slight nexus between the defendant and the crime, independent of the DNA, is likely to suffice to present an overall picture to the jury that satisfies them of the defendant's guilt." The converse was underscored in Lashley v Regina (2000 EWCA Crim 88), where the Court held that a conviction based on DNA evidence from a cigarette at the crime scene, with nothing else linking the accused to the offence, was unsafe and ought not to have been left to the jury.

In India, the corroborative role of DNA evidence is particularly critical in criminal trials where the prosecution builds its case on circumstantial evidence. The court must look for independent nexus beyond the DNA match. DNA evidence corroborates; it does not substitute for the entire chain of circumstantial proof.

The Sheena Bora Murder Case and DNA Evidence

The Sheena Bora murder case, which came before the Mumbai Sessions Court and captivated the country's attention, is a striking illustration of how DNA evidence functions as part of a wider web of circumstantial evidence. The body of Sheena Bora, found in a forest in Raigad district, had decomposed to a skeleton by the time it was discovered in 2012 — three years after her death. The primary identification of the skeletal remains as those of Sheena Bora was made through forensic DNA analysis, where a sample from the remains was matched against the DNA of her biological mother (from whom she had been separated). This is a textbook application of what forensic scientists call "kinship analysis" or "familial DNA matching."

The case powerfully illustrates the three functions that DNA evidence performs in a circumstantial case. First, it performs the function of identity — establishing that the body found was indeed that of the missing person. Without this step, there could be no corpus delicti, no murder charge, and no trial. Second, it performs the function of corroboration — it confirmed witness accounts and call data records placing the accused in proximity to the victim and the body. Third, it constitutes an independent link in the chain of circumstances. In circumstantial cases, no single piece of evidence is decisive; every link must be proved. DNA evidence here was one such critical and scientifically verifiable link.

The case also exposed a practical challenge that Indian law has not adequately resolved: the absence of a DNA Profiling Act. India's Draft DNA Profiling Bill and the DNA Data Bank Bill have been in legislative limbo for years. In the absence of dedicated legislation, courts have been forced to rely on the general framework of Section 45 IEA/Section 39 BSA and the provisions of the CrPC. The reliability of DNA evidence is also dependent on chain of custody — the manner in which samples are collected, sealed, transported, and stored — and courts in India have shown increasing awareness of this. A DNA report that cannot account for its chain of custody from collection to analysis is vulnerable to challenge.

Evidentiary Value: Cannot Compel, Can Infer

A profound tension runs through Indian jurisprudence on DNA testing: the right against self-incrimination versus the demands of justice. In Selvi v State of Karnataka (2010 7 SCC 263), the Supreme Court held that involuntary administration of tests that require a person's active participation violates Article 20(3) of the Constitution. The Court indicated that DNA tests, when they require active consent, cannot be forcibly administered. However, the courts have consistently held that a refusal to undergo a DNA test, when a prima facie case exists, permits the drawing of an adverse inference under Section 114 IEA (now Section 136 BSA), as clarified in Sharda v Dharmpal (AIR 2003 SC 3450) and Bhabani Prasad Jena v Convenor Secretary, Orissa State Commission for Women (AIR 2010 SC 2851). The principle is: you cannot be compelled to open the door, but your refusal to open it when asked reasonably may itself speak volumes.

The Problem of Footprint Evidence

Scientific Basis and Statutory Footing

The question of footprint evidence occupies an interesting position at the intersection of Section 45 (expert opinion), Section 73 IEA / Section 72 BSA (comparison of impressions), and Section 9 IEA / Section 7 BSA (identity of persons). The science of footprint identification — like the science of handwriting — is not a fully developed or exact science. As the courts have noted, "the word science occurring in Section 45 is comprehensive enough to include the opinion of an expert in footprint." However, its reliability is significantly more limited than fingerprint science.

Section 72 of the BSA, 2023 (corresponding to Section 73 IEA) specifically provides that in order to ascertain whether a signature, writing, or seal is that of the person by whom it purports to have been written, any signature, writing, or seal admitted or proved to have been written by that person may be compared. The section applies also, with necessary modifications, to "finger impressions." Courts have extended its application to include shoe and foot impressions when read with the expert opinion provisions.

Deciding the Problem Case

Now turning to the specific problem in the question: a pair of shoes was recovered from the house of the accused. The impression made by those shoes tallied with the mould prepared from footprints found at the crime scene. The trial court used this as a circumstance while holding the accused guilty. On appeal, this finding is assailed.

The answer is clear: the appellate court should not disturb this finding, provided the evidence meets certain conditions. Here is the reasoning, drawing on both statute and case law.

The evidence of the shoe impression matching the mould is admissible under Section 45 IEA / Section 39 BSA, as the opinion of a forensic science expert who compared the impressions. It falls squarely within the science of forensic identification. Under Section 9 IEA / Section 7 BSA, facts that fix the identity of any person are relevant — and the identity of the person who visited the crime scene is precisely the fact in issue. The recovery of the shoes from the accused's house, proved through the recovery panchanama and the testimony of the investigating officer, is also independently relevant under Section 27 IEA / Section 23 BSA, which renders admissible the discovery of a fact in consequence of information received from an accused person in custody. If the shoes were discovered pursuant to a disclosure statement by the accused, that disclosure itself is a relevant and admissible circumstance.

The Supreme Court in cases dealing with footprint evidence has consistently held that while "the science of identification is a rudimentary science and not much reliance can be placed on the result of such identification," track evidence "can be relied upon as a circumstance which, along with other circumstances, would point to the identity of the culprit." The critical qualification is that footprint evidence, like DNA evidence and handwriting evidence, is corroborative in character. It cannot, by itself, ground a conviction. But when it is one link in a chain of circumstantial evidence — as it appears to be in this problem — it forms a legitimate and admissible link.

The appellate court would therefore be justified in upholding the trial court's reliance on this evidence, provided:

The expert who compared the impressions was properly qualified and gave reasons for the opinion, not merely a bald conclusion.
The mould from the crime scene and the shoes from the accused's house were both properly produced and exhibited, with unbroken chain of custody.
The shoe impression evidence was not the sole basis of conviction but formed part of a broader circumstantial chain pointing to the guilt of the accused.
The comparison was done before the court, or the expert testified orally and was available for cross-examination — consistent with the principle in Section 60 IEA / Section 57 BSA that oral evidence must be direct and the evidence of an expert must come from the expert himself.

If all these conditions are satisfied, the conviction is sustainable. The impression-mould match, recovery of the shoes from the accused, and the expert's testimony together constitute a legitimate evidentiary circumstance. Conviction on circumstantial evidence requires that the circumstances be incompatible with the innocence of the accused — and a shoe matching a crime scene mould, recovered from the accused's home, is precisely the kind of link that, combined with others, satisfies that test.

The Larger Picture: Circumstantial Evidence and Expert Science

What unites DNA evidence, footprint evidence, and all forms of expert scientific testimony is the fundamental principle that expert opinion is an aid to the court, not a substitute for judicial reasoning. The court does not surrender its function to the scientist. It evaluates the basis of the opinion, examines the methodology, and considers whether the conclusion follows logically from the data. As the Supreme Court has observed, "an expert deposes and does not decide. His duty is to furnish the Judge with the necessary scientific criteria for testing the accuracy of his conclusion, so as to enable the Judge to form his own independent judgment by the application of those criteria to the facts proved in evidence."

Under Section 46 IEA / Section 40 BSA, facts that support or are inconsistent with expert opinions are themselves relevant — permitting the accused to adduce counter-scientific evidence to challenge prosecution experts. This provision ensures that scientific evidence does not become a one-way street and that the adversarial system retains its integrity even in technically complex cases. The challenge for Indian criminal justice — as the Sheena Bora case so dramatically illustrated — is to build institutional capacity, establish chain-of-custody protocols, and eventually enact a dedicated DNA legislation that gives the courts a principled and predictable framework for handling this most potent of forensic tools.