DNA Evidence under the Bharatiya Sakshya Adhiniyam, 2023: Admissibility, Compulsion, Evidentiary Value and Case Laws

DNA profiling is the most powerful identification evidence the courts have ever had. It can exclude a suspect with something approaching certainty and can include him with a probability expressed in figures no other discipline can offer. It has also produced the sharpest confrontation in Indian evidence law between scientific fact and legal presumption, and the Supreme Court has now held that where the two conflict, science prevails.

1. How the Evidence Reaches the Court

Section 39(1), BSA

When the Court has to form an opinion upon a point of foreign law or of science or art, or as to identity of handwriting or finger impressions, the opinions upon that point of persons specially skilled in such foreign law, science or art, or in questions as to identity of handwriting or finger impressions, or in any other field, are relevant facts. Such persons are called experts.

A DNA report is the opinion of an expert and is relevant under Section 39(1). The grounds of that opinion are relevant under Section 45, and facts supporting or contradicting it are relevant under Section 40. Nothing in the Adhiniyam deals specially with DNA, and the entire body of law about it has been built by the courts on these general provisions.

What a profile is may be stated briefly. Certain regions of human DNA contain short sequences that repeat a variable number of times, and the number of repeats at each region differs between individuals. Examining a sufficient number of such regions produces a profile which, apart from identical twins, is effectively unique. Comparison of two profiles yields one of three results: an exclusion, where they differ at any region and the samples cannot have come from the same person; an inclusion, where they match at every region examined; or an inconclusive result, where the sample is too degraded or too small to support a comparison.

2. Exclusion and Inclusion Are Not Equivalent

This is the point most often lost, and it governs how the evidence should be treated.

An exclusion is close to conclusive. If the profile from the crime scene differs from the profile of the accused at even one region, the samples did not come from the same person, and no statistical qualification is needed. Subject to the sample being what it is said to be and the examination being competent, an exclusion ends the matter.

An inclusion is a statement of probability. It says that the accused's profile matches, and that the probability of a randomly selected unrelated person matching by chance is some stated figure. That figure depends on the number of regions examined and on the frequency of the profile in the relevant population, and it must be stated. A report that says the profiles 'matched' without saying how many regions were compared or what the match probability is has not told the court what it needs to know.

⚠ A match probability is not a probability of guilt

The figure a DNA report gives is the probability that an unrelated person chosen at random would share the profile. It is not the probability that the accused is innocent, and treating it as such reverses the reasoning. A match places the accused within the group of persons who could have left the sample; the size of that group depends on the figure. What the match cannot say is how the sample came to be where it was found, and that remains a matter for the other evidence.

3. Where DNA Evidence Is Used

Four settings account for most of the litigation.

Identification of the offender. Biological material from the scene or from the victim is compared with a sample from the accused. This is the commonest use in sexual offences and in homicide, and it is here that the evidence is at its most powerful, because such material is ordinarily left in circumstances that admit of no innocent explanation.

Identification of the deceased. Where a body is decomposed, dismembered or burnt beyond recognition, comparison with samples from relatives establishes identity. In mass casualty situations this is frequently the only method available.

Paternity and maternity. The most litigated civil application, arising in succession disputes, maintenance proceedings and matrimonial cases, and the setting in which the conflict with the statutory presumption of legitimacy arises.

Exculpation. A profile from the scene that excludes the accused is among the strongest defences available, and it operates under Section 9 as a fact inconsistent with a fact in issue, quite apart from its status as expert opinion.

4. Compelling a Sample

Two questions arise: whether a person may be compelled to provide a sample, and whether a court may direct that a test be conducted. They are distinct, and the answers differ between criminal and civil proceedings.

4.1 The constitutional position

Article 20(3), Constitution of India

No person accused of any offence shall be compelled to be a witness against himself.

📖 State of Bombay v. Kathi Kalu Oghad, AIR 1961 SC 1808

Held: An eleven-Judge Bench held that 'to be a witness' means imparting knowledge in respect of relevant facts by an oral statement or a statement in writing. Giving thumb impressions, specimen signatures, handwriting or samples for comparison does not amount to being a witness against oneself, because such material furnishes only a means of comparison and does not convey any personal knowledge of a relevant fact. Mere custody does not by itself amount to compulsion.

Ratio: Physical and identificatory material falls outside Article 20(3). A blood or tissue sample conveys no personal knowledge and may therefore be compelled.

📖 Selvi v. State of Karnataka, (2010) 7 SCC 263

Held: The compulsory administration of narco-analysis, polygraph examination and the Brain Electrical Activation Profile test violates Article 20(3), because the results convey personal knowledge and amount to testimonial compulsion. The Court expressly distinguished techniques involving bodily substances such as blood, semen and hair, which do not convey personal knowledge and are outside the protection. Material subsequently discovered with the help of a voluntarily administered test may be admitted, in line with the discovery provision.

Ratio: The line is between testimonial and physical material. DNA sampling falls on the physical side and is not protected by Article 20(3).

On the criminal side, the Bharatiya Nagarik Suraksha Sanhita, 2023 carries forward the provisions permitting the medical examination of an accused at the request of a police officer, including the taking of blood, blood stains, semen, swabs, sputum, sweat and hair samples, and the provisions relating specifically to the examination of a person accused of rape. Read with Kathi Kalu Oghad, these permit samples to be taken without offending the Constitution.

4.2 Civil proceedings

In civil litigation there is no equivalent statutory power, and the position has been worked out by the courts. The consistent theme is that a test will not be ordered as a matter of course.

📖 Goutam Kundu v. State of West Bengal, (1993) 3 SCC 418

Held: Courts in India cannot order a blood test as a matter of course. There must be a strong prima facie case, and the applicant must establish the need for such a test. The court must consider the consequences of ordering it, including whether it would brand a child as illegitimate or the mother as unchaste. No one can be compelled to give a sample of blood for analysis, and an adverse inference may be drawn against a party who refuses. The presumption under Section 112 of the Indian Evidence Act is a conclusive presumption which can be displaced only by proof of non-access.

Ratio: The governing restraint. A test is ordered only on strong material, nobody is physically compelled, and refusal carries a consequence.

📖 Sharda v. Dharmpal, (2003) 4 SCC 493

Held: A matrimonial court has the power to order a person to undergo a medical examination, and passing such an order would not violate the right to personal liberty under Article 21. The court should exercise the power only if the applicant has a strong prima facie case and there is sufficient material before it. If, despite the order, the person refuses to submit to the examination, the court will be entitled to draw an adverse inference against him.

Ratio: The power exists, is exercised on strong material, and refusal is met with an adverse inference rather than physical compulsion.

The mechanism these decisions produce is worth stating plainly. A court does not force a person to give a sample. It makes an order; if the order is disobeyed, it draws an inference under Section 119 that the evidence withheld would have been unfavourable. In practice this operates as effective compulsion in most cases, while avoiding the difficulties that physical compulsion would present.

5. DNA and the Presumption of Legitimacy

The most interesting question DNA evidence has raised in Indian law is what happens when a scientific result contradicts a statutory presumption expressed as conclusive proof.

Section 116, BSA — Birth during marriage, conclusive proof of legitimacy

The fact that any person was born during the continuance of a valid marriage between his mother and any man, or within two hundred and eighty days after its dissolution, the mother remaining unmarried, shall be conclusive proof that he is the legitimate son of that man, unless it can be shown that the parties to the marriage had no access to each other at any time when he could have been begotten.

The presumption is one of only two instances of conclusive proof in the Adhiniyam, the other being Section 35 on judgments in rem. By force of Section 2(1)(b) the court must regard legitimacy as proved and may not allow evidence to be given to disprove it. The single escape is proof of non-access, which is part of the foundational fact rather than a right of rebuttal.

📖 Nandlal Wasudeo Badwaik v. Lata Nandlal Badwaik, (2014) 2 SCC 576

Held: Where a DNA test has in fact been conducted and its result excludes paternity, the result must prevail. When there is a conflict between a conclusive proof envisaged by law and a fact established by science, the latter must prevail, since the presumption under Section 112 is a legal fiction whereas the DNA report is a matter of scientific accuracy. The Court nevertheless reiterated that such a test is not to be directed as a matter of routine.

Ratio: A reliable DNA exclusion displaces even a conclusive statutory presumption.

⚠ How the two lines of authority work together

Goutam Kundu makes the test difficult to obtain; Nandlal Badwaik makes it decisive once obtained. The practical result is a two-stage enquiry. At the first stage the court asks whether there is a strong prima facie case justifying an order for testing, and refuses in the great majority of applications. At the second, where a test has been conducted and the result is reliable, the court gives effect to it notwithstanding Section 116. The presumption therefore continues to do its work in every case where no test is ordered, which is most of them.

6. Judicial Reception in Criminal Cases

📖 Dharam Deo Yadav v. State of Uttar Pradesh, (2014) 5 SCC 509

Held: The court must be conscious of the fact that a scientific and technical advancement in the field of investigation has taken place. DNA profiling is an accepted method of identification, and courts should not shy away from placing reliance on scientific evidence where it is properly collected and proved. The Court emphasised the need for the investigating agency to adopt scientific methods and for the prosecution to establish the integrity of the samples from collection to examination.

Ratio: DNA evidence is to be received and acted upon, subject to proof of the integrity of the samples.

📖 Mukesh v. State (NCT of Delhi), (2017) 6 SCC 1

Held: The Court accepted DNA evidence connecting the accused with the victim and with the scene, holding that the DNA report and the testimony of the expert established the matches relied upon. It observed that DNA profiling is a scientifically reliable method and that its results, where the samples have been properly collected, sealed and examined, are of a high degree of probative value. Objections to the DNA evidence founded on the possibility of tampering were rejected in the absence of any material suggesting that the samples had been interfered with.

Ratio: DNA evidence properly collected and proved carries a high degree of probative value, and objections must rest on material rather than on theoretical possibility.

7. What Must Be Proved

A DNA report proves what the samples examined contained. Everything connecting those samples to the accused, the victim and the scene must be established by ordinary evidence, and this is where such cases are most often decided.

Collection. Where, when, by whom and from whom each sample was taken; the condition of the source; and, where the sample came from the accused, the authority under which it was taken.
Sealing. That each sample was sealed at the point of collection, that the seal was described, and that a specimen seal was preserved for comparison.
Separation. That samples from the accused and from the scene or victim were collected, packed and transmitted separately, since contamination is the standard objection and separate handling is the answer to it.
Transmission. That the sealed parcels reached the laboratory in the same condition, with the carrier examined and the receipt proved.
Receipt. That the seals were intact on arrival and matched the specimen, and that the parcels were stored securely until examination.
Examination. The method used, the number of loci examined, the controls run, and the match probability calculated with reference to the relevant population.

⚠ Contamination is the standard objection and the answer is procedural

Because human biological material transfers readily and the technique amplifies minute quantities, contamination is the first line of attack on any DNA case. It cannot be answered by asserting that the laboratory is careful. It is answered by proving that the samples were separately collected, separately sealed, separately transmitted and separately handled, and that appropriate controls were run. Where the record shows the accused's sample and the crime scene sample packed together or handled in the same session, the objection is a serious one.

8. Limitations

Four limitations recur and should be put to the expert in every contested case.

A match does not explain presence. DNA establishes that material from a person was at a place. It says nothing about when it got there or how. Where the accused had lawful occasion to be present, a match on a surface he might innocently have touched proves very little.

Partial profiles support weaker conclusions. Where the sample is degraded or minute, only some loci may be readable, and the match probability falls correspondingly. A report based on a partial profile must state how many loci were obtained, and the figure must be recalculated accordingly.

Mixed samples are difficult to interpret. Where biological material from more than one person is present, separating the contributions involves judgment, and different analysts may differ. The expert should be asked how many contributors were identified and on what basis.

Relatives share profiles. The match probability is calculated for an unrelated person. Where a close relative of the accused was also present or had access, the figure understates the possibility of a coincidental match, and this should be addressed rather than ignored.

9. The Position Stated Shortly

A DNA report is expert opinion under Section 39(1), and the grounds of the opinion are relevant under Section 45.
Exclusion is close to conclusive; inclusion is a statement of probability, and the match probability must be stated.
A match probability is not a probability of guilt, and treating it as such reverses the reasoning.
Taking a sample does not offend Article 20(3), because bodily material conveys no personal knowledge — Kathi Kalu Oghad, confirmed in Selvi.
In civil proceedings a test is not ordered as a matter of course. A strong prima facie case is required, nobody is physically compelled, and refusal attracts an adverse inference.
A reliable DNA exclusion displaces even the conclusive presumption in Section 116 — Nandlal Badwaik — though the test will rarely be ordered in the first place.
Everything turns on the integrity of the samples, and contamination is answered by proof of separate collection, sealing, transmission and handling.
A match establishes presence of material, not participation in the offence, and the remaining circumstances must supply that.

10. Related Topics and Provisions

Topic or provision	Connection
Forensic Evidence	Chain of custody, class and individual characteristics, and the statutory framework for collection
Expert and Opinion Evidence — Sections 39 to 45	The statutory scheme in full
Nature and Evidentiary Value of Expert Evidence	The advisory character of expert opinion and the requirement of reasons
Presumptions under the Law of Evidence	Section 116, and the meaning of conclusive proof in Section 2(1)(b)
Confession and Article 20(3)	The line between testimonial and physical material
Section 9, BSA	Facts inconsistent with a fact in issue — the route for an exculpatory profile
Section 119, Illustration (g), BSA	The adverse inference from withholding evidence, which gives an order for testing its force
Sections 51 and 52, BNSS, 2023	Medical examination of an accused, and of a person accused of rape