Forensic evidence is admissible in Indian criminal trials mainly as the opinion of a person “specially skilled” in science or any other field. The rule is Section 39 of the Bharatiya Sakshya Adhiniyam, 2023 (BSA), formerly Section 45 of the Indian Evidence Act, 1872: when the court has to form an opinion “upon a point of foreign law or of science or art, or any other field, or as to identity of handwriting or finger impressions”, the opinions of such persons “are relevant facts and such persons are called experts”. The words “or any other field” are new; the old Section 45 covered only foreign law, science, art, handwriting and finger impressions. The report of a Government forensic laboratory can be read in evidence without calling the scientist, under Section 329 of the Bharatiya Nagarik Suraksha Sanhita, 2023 (BNSS), formerly Section 293 of the Code of Criminal Procedure (CrPC), but the court may summon the scientist, and a disputed report usually has to be proved through the person who made it.
Admissible does not mean conclusive. An expert “is not a witness of fact and his evidence is really of an advisory character” (Ramesh Chandra Agrawal v. Regency Hospital, 2009). DNA evidence is only as good as the way the samples were collected, sealed, stored and sent: in Kattavellai @ Devakar v. State of Tamil Nadu (15 July 2025) the Supreme Court set aside a death-sentence conviction, finding among other things that the DNA evidence had been rendered “unusable”, and ordered a Chain of Custody Register in every DNA case. Narco-analysis, polygraph and brain-mapping tests cannot be forced on anyone (Selvi v. State of Karnataka, 2010).
Forensic evidence in India at a glance
- Main rule: Section 39 BSA (formerly Section 45 Evidence Act) makes the opinion of experts on science, art, foreign law, “any other field”, handwriting and finger impressions a relevant fact.
- Electronic evidence: Section 39(2) BSA (formerly 45A) – the opinion of the Examiner of Electronic Evidence under Section 79A of the IT Act is a relevant fact; computer output needs the certificate in Section 63 BSA (formerly 65B).
- FSL reports: Section 329 BNSS (formerly 293 CrPC) – a report of a listed Government scientific expert “may be used as evidence”; the court “may, if it thinks fit, summon and examine” the expert.
- Disputed reports: Section 330 BNSS – documents are admitted or denied within 30 days of supply, and no expert is called unless a party disputes the report; the court may still summon the expert under Section 329(2). In Irfan v. State of M.P. (2025, under the CrPC) a capital trial was vitiated because the court relied on a DNA report without the scientists’ evidence.
- Collection: Section 176(3) BNSS – a forensic expert visits the scene of offences punishable with seven years or more, from the date each State notifies; Section 105 BNSS – searches and seizures are video-recorded.
- Samples from the accused: Sections 51–53 BNSS (formerly 53, 53A, 54 CrPC) allow medical examination including blood, semen, hair and DNA profiling; Section 349 BNSS covers specimen signatures, finger impressions, handwriting and voice samples.
- Narco, polygraph, brain mapping: never by force; even a voluntary test result is not itself evidence, though facts discovered with its help can be proved (Selvi, 5 May 2010).
- DNA: samples should reach the laboratory within 48 hours and every movement must be entered in a Chain of Custody Register (Kattavellai, 15 July 2025).
Reviewed and updated by Century Law Firm, Delhi – October 2026. Statutory references are to the Acts as in force on that date. The Bharatiya Sakshya Adhiniyam, 2023, the Bharatiya Nagarik Suraksha Sanhita, 2023 and the Criminal Procedure (Identification) Act, 2022 are quoted from India Code (each as on 6 October 2025, the current versions on 23 October 2026), the Constitution from the Legislative Department’s 2026 edition, and the judgments from the Supreme Court’s own copies.
What is forensic evidence, and how does Indian law classify it?
No Indian statute defines “forensic evidence”. In practice it means facts found by scientific examination of things connected with a crime: blood and body fluids, DNA, fingerprints, firearms and cartridges, poisons and drugs, documents and handwriting, and data on phones and computers. The law reaches these facts in three ways.
- As oral evidence: the scientist or doctor who examined the material gives evidence in court. Section 55 BSA (formerly Section 60 Evidence Act) says that if oral evidence refers to “an opinion or to the grounds on which that opinion is held, it must be the evidence of the person who holds that opinion on those grounds”.
- As documentary evidence: the laboratory report, post-mortem report or medico-legal report is a document. “Evidence” in Section 2(1)(e) BSA includes “all documents including electronic or digital records produced for the inspection of the Court”.
- As material objects: the weapon, the clothes, the sealed samples. Under the second proviso to Section 55 BSA, where oral evidence refers to “the existence or condition of any material thing other than a document, the Court may, if it thinks fit, require the production of such material thing for its inspection”.
The Supreme Court uses the same classification. In Selvi (2010) it distinguished “personal testimony” from “material evidence such as bodily substances and other physical objects”, recording the view in Kathi Kalu Oghad that finger impressions and specimen writing “belong to the third category of material evidence which is outside the limit of ‘testimony'”. This decides whether an accused can be made to give a sample: bodily samples can be taken under the BNSS, but a test that extracts what a person knows cannot be forced.
Types of forensic evidence and the law that applies
Laboratories are organised by discipline; Himachal Pradesh’s Directorate of Forensics Services, for example, lists Biology and Serology, Chemistry and Toxicology, Documents and Photography, Physics and Ballistics, DNA, Forensic Psychology and Digital Forensics, and a Fingerprint Bureau. The table links each type to the provisions that usually apply.
| Type of evidence | Examples | Main provisions |
|---|---|---|
| Biological and DNA | Blood, semen, swabs, hair, nail clippings, saliva on objects | Sections 51–53 and 184 BNSS (collection); Section 329(4)(e)–(f) BNSS (FSL, Serologist); Section 39 BSA |
| Fingerprints and other measurements | Finger, palm and foot prints, iris scans, photographs | Section 39(1) and 72(3) BSA; Section 349 BNSS; Criminal Procedure (Identification) Act, 2022; Section 329(4)(c) BNSS (Finger Print Bureau) |
| Chemical and toxicological | Poison in viscera, drugs, alcohol | Section 329(4)(a) BNSS (Chemical Examiner); Section 39 BSA, illustration (a) on poison |
| Ballistics and explosives | Firearms, cartridges, explosive residue | Section 329(4)(b) and (e) BNSS (Chief Controller of Explosives; FSL); Section 39 BSA |
| Questioned documents | Handwriting, signatures, seals, printed notes | Sections 39, 41 and 72 BSA; Section 328 BNSS (Examiners of Questioned Documents); Section 349 BNSS |
| Medical and post-mortem | Injury reports, post-mortem reports | Sections 53, 194 and 326 BNSS; Section 39 BSA |
| Digital and electronic | Phone data, CCTV, e-mails, server logs | Sections 39(2) and 63 BSA; Sections 105 and 193(3) BNSS |
| Psychological and psychiatric | Opinion on unsoundness of mind | Section 39 BSA, illustration (b) |
Section 39 BSA (formerly Section 45 Evidence Act): opinions of experts
Section 39(1) BSA reads: “When the Court has to form an opinion upon a point of foreign law or of science or art, or any other field, 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 any other field, or in questions as to identity of handwriting or finger impressions are relevant facts and such persons are called experts.”
Its three illustrations are the classic forensic questions: whether a death was caused by poison (opinions on “the symptoms produced by the poison” are relevant); whether a person was, by unsoundness of mind, incapable of knowing the nature of his act; and whether a document was written by a particular person, judged by comparison with a document “proved or admitted to have been written by A”.
Section 39(2) BSA, which was Section 45A of the Evidence Act, deals with digital material: “When in a proceeding, the court has to form an opinion on any matter relating to any information transmitted or stored in any computer resource or any other electronic or digital form, the opinion of the Examiner of Electronic Evidence referred to in section 79A of the Information Technology Act, 2000 (21 of 2000), is a relevant fact.” The Explanation adds that such an Examiner “shall be an expert”.
What changed from Section 45 of the Evidence Act
The firm’s comparison data, checked against the Gazette text, records one change of substance in Section 39(1): the words “or any other field” have been added, so the scope “is expanded greatly”. The old Section 45, as quoted by the Supreme Court in 2009, applied to “a point of foreign law, or of science, or art, or as to identity of hand writing or finger-impressions”. Section 45A became Section 39(2) without change of substance. Judgments decided under the Evidence Act cite Section 45; because Section 39 keeps its words and only adds to them, the firm’s reading is that those judgments remain the guide.
Related sections: 40, 41, 45, 55 and 72 BSA
| BSA section (old Evidence Act section) | What it says |
|---|---|
| 40 (46) | Facts, “not otherwise relevant”, are relevant “if they support or are inconsistent with the opinions of experts”. |
| 41 (47 and 47A) | Opinion of a person acquainted with someone’s handwriting or signature is relevant; under 41(2) the Certifying Authority’s opinion on an electronic signature is relevant. |
| 45 (51) | When an opinion is relevant, “the grounds on which such opinion is based are also relevant”; “An expert may give an account of experiments performed by him”. |
| 55 (60) | An opinion must be proved by the person who holds it; a published treatise can be used only if the author is dead, cannot be found, has become incapable of giving evidence, or cannot be called without unreasonable delay or expense. |
| 72 (73) | The court may compare a disputed signature, writing or seal with an admitted or proved one, and may direct a person present in court to write; the section “applies also, with any necessary modifications, to finger impressions”. |
When is forensic evidence admissible, and how much weight does it carry?
Three separate questions arise for every piece of forensic evidence: is it relevant, has it been proved, and how much weight should it get? Section 39 BSA answers the first: an expert’s opinion on a scientific point is a relevant fact. Proof depends on how the evidence reaches the court: through the expert’s own testimony, through a report admissible under Section 329 BNSS, or through an undisputed document under Section 330 BNSS. Weight is for the judge.
Who counts as an expert
The BSA does not list qualifications. The Supreme Court, explaining the old Section 45 in Ramesh Chandra Agrawal v. Regency Hospital Ltd. (11 September 2009), a medical-negligence appeal, relied on State of H.P. v. Jai Lal: to treat a witness as an expert “it has to be shown that he has made a special study of the subject or acquired a special experience therein or in other words that he is skilled and has adequate knowledge of the subject”. The same judgment, citing a textbook, listed three further requirements for expert evidence to be admissible: “i) that the expert must be within a recognized field of expertise ii) that the evidence must be based on reliable principles, and iii) that the expert must be qualified in that discipline.” The first condition is that expert evidence is needed at all: “The test is that the matter is outside the knowledge and experience of the lay person.”
Expert opinion is advisory, not binding
The same judgment explains the expert’s role: “It is not the province of the expert to act as Judge or Jury.” In the court’s words, “An expert is not a witness of fact and his evidence is really of an advisory character”; opinion that is “intelligible, convincing and tested becomes a factor and often an important factor for consideration along with other evidence of the case”, and its credibility “depends on the reasons stated in support of his conclusions and the data and material furnished”. The Court also quoted State (Delhi Administration) v. Pali Ram: “no expert would claim today that he could be absolutely sure that his opinion was correct”.
This is why Section 45 BSA makes the grounds of an opinion relevant: a report that sets out the samples, seals, methods and results can be tested in cross-examination; a bare conclusion is weak.
Is the American “Daubert” test part of Indian law?
No. Daubert v. Merrell Dow Pharmaceuticals (1993) is a decision of the United States Supreme Court, which the Supreme Court of India described in Selvi (2010): it looks at whether a technique “can be and has been tested”, peer review, “its known or potential error rate”, controlling standards and scientific acceptance. Indian courts apply Section 39 BSA and the requirements in judgments such as Ramesh Chandra Agrawal, and test reliability through the grounds of the opinion and cross-examination. The earlier version of this post presented “known error rate” and “peer review” as Indian requirements and called Daubert a precedent of an unnamed “Supreme Court”; both points have been corrected.
How forensic evidence reaches the court: the BNSS procedure
The BNSS, in force since 1 July 2024, added several forensic steps that the CrPC did not have: a forensic expert’s visit to the scene of serious offences, video recording of searches and seizures, and a record of the “sequence of custody” of electronic devices in the police report. The infographic shows the path; the sections below explain each step.
Prepared by Century Law Firm from the Bharatiya Nagarik Suraksha Sanhita, 2023 and the Bharatiya Sakshya Adhiniyam, 2023 (India Code, as on 6 October 2025) and the Supreme Court’s judgments in Ramesh Chandra Agrawal (2009), Irfan (2025) and Kattavellai (2025).
Forensic expert at the crime scene: Section 176(3) BNSS
Section 176 BNSS corresponds to Section 157 CrPC (procedure for investigation), but sub-section (3) is new: “On receipt of every information relating to the commission of an offence which is made punishable for seven years or more, the officer in charge of a police station shall, from such date, as may be notified within a period of five years by the State Government in this regard, cause the forensic expert to visit the crime scene to collect forensic evidence in the offence and also cause videography of the process on mobile phone or any other electronic device.”
The duty applies only from the date notified by each State Government, so whether it is in force depends on that State’s notification. The table of State notifications under the BNSS kept by the Bureau of Police Research and Development (Ministry of Home Affairs, last updated 19 October 2026) lists only Rajasthan against Section 176(3), with a notification dated 7 October 2024; check your own State’s Gazette for the current position. The proviso adds: “where forensic facility is not available in respect of any such offence, the State Government shall, until the facility in respect of that matter is developed or made in the State, notify the utilisation of such facility of any other State.”
Video recording of search and seizure: Section 105 BNSS
Section 105 BNSS has no counterpart in the CrPC. It says: “The process of conducting search of a place or taking possession of any property, article or thing under this Chapter or under section 185, including preparation of the list of all things seized in the course of such search and seizure and signing of such list by witnesses, shall be recorded through any audio-video electronic means preferably mobile phone and the police officer shall without delay forward such recording to the District Magistrate, Sub-divisional Magistrate or Judicial Magistrate of the first class.” Section 185(2) BNSS (formerly Section 165 CrPC) repeats that a search by a police officer during investigation “shall be recorded through audio-video electronic means preferably by mobile phone”.
For forensic evidence the seizure is the first link in the chain of custody: a video showing where an item was found, how it was packed and who signed the seizure list makes later questions about planting or tampering easier to answer.
Medical examination of the accused: Sections 51, 52 and 53 BNSS
Section 51 BNSS (formerly Section 53 CrPC) allows a registered medical practitioner, at the request of any police officer, to examine a person arrested for an offence where “there are reasonable grounds for believing that an examination of his person will afford evidence as to the commission of an offence”, using “such force as is reasonably necessary”. The Explanation is the core of forensic collection: “‘examination’ shall include the examination of blood, blood stains, semen, swabs in case of sexual offences, sputum and sweat, hair samples and finger nail clippings by the use of modern and scientific techniques including DNA profiling”. A woman is examined “only by, or under the supervision of, a female registered medical practitioner”, and the report goes to the investigating officer “without any delay” (Section 51(2) and (3)).
Section 52 BNSS (formerly Section 53A CrPC) governs examination of a person arrested for rape or attempt to rape; the report must include “the description of material taken from the person of the accused for DNA profiling” and “state precisely the reasons for each conclusion arrived at”. Section 53 BNSS (formerly Section 54 CrPC) requires every arrested person to be examined by a medical officer soon after arrest, a record that protects the arrested person too; see the firm’s guide to the rights of an arrested person.
Medical examination of a rape survivor: Section 184 BNSS
Section 184 BNSS (formerly Section 164A CrPC) requires the woman to be sent to a registered medical practitioner “within twenty-four hours from the time of receiving the information”, but only “with the consent of such woman or of a person competent to give such consent on her behalf”. The report must describe the “material taken from the person of the woman for DNA profiling”, must record that consent was obtained, and must reach the investigating officer “within a period of seven days” (the CrPC said “without delay”). Sub-section (7) is explicit: nothing in the section makes lawful “any examination without the consent of the woman”.
Specimens, fingerprints and “measurements”
Section 349 BNSS (formerly Section 311A CrPC) allows a Magistrate of the first class to order “any person, including an accused person, to give specimen signatures or finger impressions or handwriting or voice sample”. Finger impressions and voice samples are new additions. The person must ordinarily have been arrested in connection with the investigation, but a new proviso allows the Magistrate, “for the reasons to be recorded in writing”, to order a specimen “without him being arrested”.
The Criminal Procedure (Identification) Act, 2022, in force from 4 August 2022, replaced the Identification of Prisoners Act, 1920. “Measurements” include “finger-impressions, palm-print impressions, foot-print impressions, photographs, iris and retina scan, physical, biological samples and their analysis, behavioural attributes including signatures, handwriting” (Section 2(1)(b)). Convicts, persons ordered to give security for good behaviour or keeping the peace, and arrested or detained persons must, if so required, allow measurements to be taken (Section 3), but an arrested person “may not be obliged” to give biological samples “under the provisions of this section” unless the offence is against a woman or a child or punishable with imprisonment of not less than seven years. That exemption is confined to Section 3: it does not limit a medical examination under Section 51 BNSS, or an order by a Magistrate under Section 5 of the 2022 Act directing “any person to give measurements”, so a sample cannot simply be refused. The National Crime Records Bureau keeps the records for seventy-five years; those of a person with no previous conviction who is released without trial, discharged or acquitted, after exhausting all legal remedies, must be destroyed unless the court or Magistrate directs otherwise (Section 4(2)). Refusal is deemed an offence under Section 186 IPC (Section 6(2)), which the firm’s comparison data maps to Section 221 BNS; the Act’s text on India Code still refers to the CrPC and IPC.
Post-mortem and inquest: Sections 194 and 326 BNSS
In a death by suicide, violence or accident, or “under circumstances raising a reasonable suspicion that some other person has committed an offence”, the police prepare an inquest report and send it to the District or Sub-divisional Magistrate “within twenty-four hours” (Section 194 BNSS, formerly Section 174 CrPC). Under Section 194(3) the body must be sent to the nearest Civil Surgeon or other qualified medical person in specified cases, including the suspicious death of a woman within seven years of marriage and any case where “there is any doubt regarding the cause of death”. Under Section 326 BNSS (formerly Section 291 CrPC), a medical witness’s deposition taken by a Magistrate in the presence of the accused may be read in evidence; the court may, and on the application of either side shall, summon the doctor.
FSL reports: Section 329 BNSS (formerly Section 293 CrPC)
Section 329(1) BNSS is the reason most forensic reports reach the court without the scientist in the witness box: “Any document purporting to be a report under the hand of a Government scientific expert to whom this section applies, upon any matter or thing duly submitted to him for examination or analysis and report in the course of any proceeding under this Sanhita, may be used as evidence in any inquiry, trial or other proceeding under this Sanhita.”
Section 329(4) lists the Government scientific experts to whom the section applies:
- (a) any Chemical Examiner or Assistant Chemical Examiner to Government;
- (b) the Chief Controller of Explosives;
- (c) the Director of the Finger Print Bureau;
- (d) the Director, Haffkeine Institute, Bombay;
- (e) the Director, Deputy Director or Assistant Director of a Central Forensic Science Laboratory or a State Forensic Science Laboratory;
- (f) the Serologist to the Government;
- (g) “any other scientific expert specified or certified, by notification, by the State Government or the Central Government for this purpose”.
Clause (g) is wider than its CrPC counterpart: the comparison data records that the words “State Government or” and “or certified” have been added. Section 328 BNSS (formerly Section 292 CrPC) gives similar treatment to reports of Government and State Examiners of Questioned Documents and certain Mint and forensic officers notified by the Central Government. In the firm’s reading, a report by someone outside these lists, such as a private laboratory, does not get this benefit and, if disputed, must be proved in the ordinary way, normally by examining its author; a document whose genuineness is not disputed “may be read in evidence” without proof of the signature (Section 330(3) BNSS).
When must the scientist give evidence?
Under Section 329(2), “The Court may, if it thinks fit, summon and examine any such expert as to the subject-matter of his report.” If the expert cannot attend, he may, unless the court has directed personal appearance, depute “any responsible officer working with him” who “is conversant with the facts of the case and can satisfactorily depose in Court on his behalf” (Section 329(3)).
Section 330 BNSS (formerly Section 294 CrPC) adds a timetable. When either side files documents, the other must admit or deny the genuineness of each “soon after supply of such documents and in no case later than thirty days after such supply”, although the court may relax the time for recorded reasons. A new second proviso says that “no expert shall be called to appear before the Court unless the report of such expert is disputed by any of the parties to the trial”. In practice, therefore, an accused who wants to challenge a forensic report should deny it in time and ask for the expert to be examined.
The Supreme Court has insisted on that right in serious cases. In Irfan alias Bhayu Mevati v. State of Madhya Pradesh (16 January 2025, three judges), the accused, facing a death sentence, asked to cross-examine the scientist who prepared the DNA report, with the laboratory documents and “Complete documentation of the chain of custody”. The Court held that “The failure of the trial Court to ensure the deposition of the scientific experts while relying upon the DNA report, has definitely led to the failure of justice thereby, vitiating the trial”, and remanded the case for the experts to be summoned “with the entire supporting material”.
DNA evidence and the chain of custody
DNA profiling is named in the BNSS itself (Explanation to Section 51, and Sections 52 and 184). In court, a DNA report is expert opinion under Section 39 BSA, usually from a Forensic Science Laboratory reporting under Section 329 BNSS.
The Supreme Court has repeatedly said that a DNA result is reliable only if the sample is. In Kattavellai @ Devakar v. State of Tamil Nadu (15 July 2025, three judges), it recalled its observation in Anil v. State of Maharashtra (2014) that “A DNA profile is valid and reliable, but the same depends on quality control and procedures in the laboratory”, and added that “quality control and procedures outside the laboratory matter equally as much”. It described DNA evidence as “only of probative value, subject to the condition that it is properly dealt with”.
Cases where DNA evidence was rejected
In Kattavellai the Court listed recent cases in which DNA evidence was rejected, in its own words:
| Case (as described in Kattavellai, 2025) | Why the DNA evidence failed |
|---|---|
| Manoj v. State of M.P., (2023) 2 SCC 353, three judges | The recovery “was made from an open place, and the likelihood of its contamination cannot be ruled out”; bloodstains were “disintegrated” and too little for classification tests. |
| Rahul (a Delhi case from the Dwarka Courts) | Samples “remained in the police Malkhana for two months”, so tampering could not be ruled out; the lower courts had not examined the basis of the DNA findings or whether the techniques “had been reliably applied”. |
| Prakash Nishad v. State of Maharashtra, (2023) 16 SCC 357 | Unexplained delay in sending samples to the FSL, so “the concomitant prospect of contamination could not be ruled out”. |
| Kattavellai itself | Vaginal swabs reached the laboratory after “a delay of 41 days” that was never explained; “large gaps in the chain of custody”; the post-mortem was conducted at the spot “without due regard to the possibility of contamination”. |
In Kattavellai, the conviction and death sentence were set aside and the appellant was ordered to be released. The Court noted that guidance on DNA collection existed in documents of the Directorate of Forensic Science Services, the Central Forensic Science Laboratory and the LNJN National Institute of Criminology and Forensic Science, but that “there is no uniformity nor there is a common procedure”.
The Supreme Court’s four directions for DNA evidence (2025)
The Court therefore issued directions “which shall be followed henceforth, in all cases where DNA Evidence is involved”. In summary:
- Collection: packaging must record the FIR number and date, the section and statute, the investigating officer and police station, and a serial number; the collection document must be signed by the medical professional, the investigating officer and independent witnesses. If independent witnesses could not be joined, the efforts made must be recorded.
- Transport: the investigating officer is responsible for getting the samples to the forensic science laboratory “with dispatch and in any case not later than 48-hours from the time of collection”; any delay must be explained in the case diary.
- Storage: while samples are stored pending trial or appeal, “no package shall be opened, altered or resealed” without the express authorisation of the trial court.
- Chain of Custody Register: “Right from the point of collection to the logical end, i.e., conviction or acquittal of the accused”, every movement must be recorded and countersigned, and the register “shall necessarily be appended as part of the Trial Court record”. Failure makes the investigating officer “responsible for explaining such lapse”.
The Directors General of Police of all States were directed to prepare sample forms of the register and send them to all districts. For electronic devices the BNSS has a statutory equivalent: the police report must state “the sequence of custody in case of electronic device” (Section 193(3)(i) BNSS, formerly Section 173 CrPC).
Narco-analysis, polygraph and brain-mapping tests: Selvi v. State of Karnataka (2010)
In Smt. Selvi v. State of Karnataka (5 May 2010), three judges of the Supreme Court (Chief Justice K.G. Balakrishnan, Justices R.V. Raveendran and J.M. Panchal) decided whether narco-analysis (an injection of sodium pentothal inducing a “hypnotic trance”), polygraph examination and the Brain Electrical Activation Profile (BEAP) test could be administered without consent. Its conclusions:
- Compulsion is unconstitutional. “The compulsory administration of the impugned techniques violates the ‘right against self-incrimination'” in Article 20(3) (“No person accused of any offence shall be compelled to be a witness against himself”), because the results “bear a ‘testimonial’ character”. It also violates personal liberty under Article 21 and is “an unjustified intrusion into the mental privacy of an individual”.
- No one may be forced, “whether in the context of investigation in criminal cases or otherwise”, and the tests cannot be read into the medical-examination provisions (then Sections 53, 53A and 54 CrPC, now Sections 51–53 BNSS).
- Voluntary results are still not evidence: “the test results by themselves cannot be admitted as evidence because the subject does not exercise conscious control over the responses”.
- Discovery is the exception: material “subsequently discovered with the help of voluntary administered test results can be admitted, in accordance with Section 27 of the Evidence Act, 1872”, now the proviso to Section 23(2) BSA.
- Safeguards: the NHRC’s 2000 Guidelines for polygraph tests “should be strictly adhered to”, with similar safeguards for the other tests: consent of the accused, a lawyer, consent recorded before a Judicial Magistrate, and the test conducted by “an independent agency (such as a hospital)” in the presence of a lawyer.
The firm’s article on confessions and admissions explains Section 23 BSA and the discovery proviso, and the post on the right to privacy explains how later judgments treat privacy under Article 21.
Digital and electronic evidence (Section 63 BSA, formerly Section 65B)
Data extracted from phones, computers and CCTV systems is governed by two rules. The opinion of an Examiner of Electronic Evidence notified under Section 79A of the IT Act is a relevant fact (Section 39(2) BSA). The record itself is proved under Section 63 BSA (formerly Section 65B Evidence Act), with a certificate that “shall be submitted along with the electronic record at each instance where it is being submitted for admission”, signed by the person in charge of the device “and an expert”, in the form in the Schedule.
Under the old Act, the official headnote of Arjun Panditrao Khotkar v. Kailash Kushanrao Gorantyal ([2020] 7 SCR 180) records that “A written certificate u/s.65B(4) is a sine qua non for admissibility of such evidence” and that “Anvar P.V., as clarified, is the law on s.65B”. The firm’s guide to electronic records and evidence under Section 63 BSA explains the certificate and the case law in detail.
Which BSA or BNSS section covers which forensic step
| Step | New section | Old section |
|---|---|---|
| Expert opinion is relevant | Section 39(1) BSA | Section 45 Evidence Act |
| Examiner of Electronic Evidence | Section 39(2) BSA | Section 45A Evidence Act |
| Facts supporting or contradicting an expert | Section 40 BSA | Section 46 Evidence Act |
| Grounds of an opinion | Section 45 BSA | Section 51 Evidence Act |
| Court’s comparison of writing and finger impressions | Section 72 BSA | Section 73 Evidence Act |
| Electronic record certificate | Section 63 BSA | Section 65B Evidence Act |
| Discovery from information of the accused | Section 23(2) proviso BSA | Section 27 Evidence Act |
| Forensic expert at the scene | Section 176(3) BNSS | None (Section 157 CrPC had no such duty) |
| Video of search and seizure | Sections 105 and 185(2) BNSS | None (Section 165 CrPC had no such proviso) |
| Medical examination of accused | Sections 51, 52, 53 BNSS | Sections 53, 53A, 54 CrPC |
| Medical examination of rape survivor | Section 184 BNSS | Section 164A CrPC |
| Specimen signatures, finger impressions, voice | Section 349 BNSS | Section 311A CrPC |
| Inquest and post-mortem | Section 194 BNSS | Section 174 CrPC |
| Deposition of medical witness | Section 326 BNSS | Section 291 CrPC |
| Reports of Mint and document examiners | Section 328 BNSS | Section 292 CrPC |
| Reports of Government scientific experts | Section 329 BNSS | Section 293 CrPC |
| Admitting or denying documents | Section 330 BNSS | Section 294 CrPC |
Any other old section can be looked up in the firm’s IPC to BNS, CrPC to BNSS and Evidence Act to BSA comparison tool; the guide to the BNS, BNSS and BSA explains the three new laws.
Challenging or relying on forensic evidence: points to check
Whether you are the accused, the victim or a witness, the same legal questions decide whether forensic evidence will hold:
- Collection: was the seizure video-recorded under Section 105 BNSS, and, where Section 176(3) has been notified, did a forensic expert visit the scene?
- Custody: do the seizure memo, seals and laboratory receipt match, and is there a Chain of Custody Register for DNA, with samples sent within 48 hours or the delay explained?
- Timing: in cases begun under the BNSS, was the report admitted or denied within 30 days of supply under Section 330 BNSS?
- Grounds: does the report give the tests, results and reasons (Section 45 BSA)? The court can call for the supporting material, as in Irfan (2025).
A conviction based on flawed forensic evidence can be challenged in appeal, as the appeals in Kattavellai and Irfan show. On compensation after long wrongful imprisonment, the Court in Kattavellai recalled its observation in V. Senthil Balaji (2024) that a clean acquittal after very long incarceration “may amount to violation of rights of the accused under Article 21 of the Constitution which may give rise to a claim for compensation”, while clarifying that it was not deciding whether “the day of reckoning with this question has arrived”; noting that in the United States statutes provide for such compensation, it said: “it is for the legislature to consider this aspect.” The firm’s article on review, revision and appeal explains the routes.
Cases that began before 1 July 2024
Under Section 531(2)(a) BNSS and Section 170(2) BSA, an investigation, inquiry, trial or appeal that was pending immediately before 1 July 2024 continues under the CrPC and the Evidence Act “as if this Sanhita had not come into force” (BSA: “as if this Adhiniyam had not come into force”). In such cases Sections 293 and 294 CrPC and Section 45 of the Evidence Act apply, and the 30-day limit in Section 330 BNSS does not.
The BSA and the BNSS came into force on 1 July 2024. Earlier judgments, including Selvi and Ramesh Chandra Agrawal, refer to Section 45 of the Evidence Act and Sections 53, 53A, 54 and 293 of the CrPC. Because Section 39 BSA keeps the words of Section 45 and only adds to them, and Section 329 BNSS repeats Section 293 CrPC with a wider clause (g), the firm’s reading is that the older judgments continue to guide courts. Duties with no CrPC counterpart, such as the forensic visit under Section 176(3) and video-recording under Section 105, arise only under the BNSS.
फॉरेंसिक साक्ष्य और विशेषज्ञ की राय – हिंदी में सारांश (Summary in Hindi)
यह हिस्सा फर्म का अपना हिंदी सारांश है। इसमें अधिनियमों के आधिकारिक हिंदी पाठ से शब्द उद्धृत नहीं किए गए हैं; जहाँ ज़रूरी लगा, अंग्रेज़ी शब्द कोष्ठक में दिए गए हैं।
फॉरेंसिक साक्ष्य क्या है? अपराध से जुड़ी चीज़ों की वैज्ञानिक जाँच से मिले तथ्य, जैसे खून और शरीर के अन्य द्रव, डीएनए, उंगलियों के निशान, हथियार और कारतूस, ज़हर और नशीले पदार्थ, लिखावट और दस्तावेज़, तथा मोबाइल-कंप्यूटर का डेटा, फॉरेंसिक साक्ष्य कहलाते हैं। अदालत में ये तीन रूपों में आते हैं: विशेषज्ञ की गवाही (मौखिक साक्ष्य), प्रयोगशाला की रिपोर्ट (दस्तावेज़ी साक्ष्य), और ज़ब्त की गई वस्तुएँ (भौतिक साक्ष्य)।
धारा 39 BSA (पहले साक्ष्य अधिनियम की धारा 45): जब अदालत को विदेशी कानून, विज्ञान, कला, “किसी अन्य क्षेत्र” (any other field), लिखावट या उंगलियों के निशान की पहचान पर राय बनानी हो, तब उस विषय में विशेष रूप से कुशल व्यक्तियों की राय प्रासंगिक तथ्य (relevant fact) है और ऐसे व्यक्ति विशेषज्ञ (experts) कहलाते हैं। “किसी अन्य क्षेत्र” शब्द नए हैं, इसलिए विशेषज्ञ राय का दायरा पहले से बड़ा हो गया है। धारा 39(2) के अनुसार इलेक्ट्रॉनिक या डिजिटल जानकारी के मामले में IT अधिनियम की धारा 79A के अंतर्गत अधिसूचित इलेक्ट्रॉनिक साक्ष्य परीक्षक (Examiner of Electronic Evidence) की राय प्रासंगिक है। धारा 45 BSA के अनुसार राय के आधार भी प्रासंगिक हैं, यानी विशेषज्ञ को बताना चाहिए कि उसने कौन-से परीक्षण किए और किस आधार पर निष्कर्ष निकाला।
विशेषज्ञ की राय बाध्यकारी नहीं है। सुप्रीम कोर्ट ने रमेश चंद्र अग्रवाल बनाम रीजेंसी हॉस्पिटल (11 सितंबर 2009) में कहा कि विशेषज्ञ तथ्य का गवाह नहीं होता और उसकी राय सलाह के रूप में होती है (“advisory character”)। अदालत रिपोर्ट के कारणों, आँकड़ों और बाकी साक्ष्य को देखकर स्वयं निर्णय करती है।
FSL रिपोर्ट – धारा 329 BNSS (पहले धारा 293 CrPC): सरकारी रासायनिक परीक्षक, फिंगर प्रिंट ब्यूरो के निदेशक, केंद्रीय या राज्य फॉरेंसिक विज्ञान प्रयोगशाला के निदेशक, उप निदेशक या सहायक निदेशक, सरकारी सीरोलॉजिस्ट और धारा में सूचीबद्ध अन्य सरकारी वैज्ञानिक विशेषज्ञों की रिपोर्ट बिना उन्हें बुलाए साक्ष्य में पढ़ी जा सकती है, पर अदालत चाहे तो विशेषज्ञ को बुला सकती है। धारा 330 BNSS के अनुसार दस्तावेज़ मिलने के 30 दिन के भीतर उन्हें स्वीकार या अस्वीकार करना होता है, और विशेषज्ञ को तभी बुलाया जाता है जब कोई पक्ष रिपोर्ट पर विवाद करे। इरफ़ान बनाम मध्य प्रदेश राज्य (16 जनवरी 2025) में सुप्रीम कोर्ट ने दोषसिद्धि रद्द करके मामला ट्रायल कोर्ट को वापस भेजा, क्योंकि डीएनए रिपोर्ट पर भरोसा करते हुए उसे तैयार करने वाले वैज्ञानिकों की गवाही नहीं कराई गई थी।
जाँच के दौरान नए नियम: धारा 176(3) BNSS के अनुसार सात वर्ष या उससे अधिक की सज़ा वाले अपराधों में, राज्य सरकार द्वारा अधिसूचित तारीख से, फॉरेंसिक विशेषज्ञ घटनास्थल पर जाकर साक्ष्य एकत्र करेगा और इस प्रक्रिया की मोबाइल फ़ोन या अन्य इलेक्ट्रॉनिक उपकरण से वीडियोग्राफी होगी। धारा 105 BNSS के अनुसार तलाशी, ज़ब्ती और ज़ब्ती सूची बनाने की पूरी प्रक्रिया की ऑडियो-वीडियो रिकॉर्डिंग, अधिमानतः मोबाइल फ़ोन से, होगी और रिकॉर्डिंग बिना देरी मजिस्ट्रेट को भेजी जाएगी।
आरोपी की चिकित्सा जाँच और नमूने: धारा 51 BNSS (पहले धारा 53 CrPC) के अंतर्गत गिरफ्तार आरोपी के खून, वीर्य, बाल, नाखून आदि की जाँच, डीएनए प्रोफाइलिंग सहित, पंजीकृत चिकित्सक कर सकता है; महिला की जाँच केवल महिला चिकित्सक द्वारा या उसकी देखरेख में होगी। धारा 349 BNSS के अंतर्गत मजिस्ट्रेट हस्ताक्षर, उंगलियों के निशान, लिखावट या आवाज़ का नमूना देने का आदेश दे सकता है। बलात्कार पीड़िता की चिकित्सा जाँच (धारा 184 BNSS) उसकी या उसकी ओर से सहमति देने में सक्षम व्यक्ति की सहमति के बिना नहीं हो सकती। दंड प्रक्रिया (पहचान) अधिनियम, 2022 (Criminal Procedure (Identification) Act, 2022) की धारा 3 के अंतर्गत, ऐसे अपराध में गिरफ्तार व्यक्ति, जो महिला या बच्चे के विरुद्ध न हो और जिसमें सात वर्ष या अधिक की सज़ा न हो, उस धारा के तहत जैविक नमूना देने के लिए बाध्य नहीं है; परंतु धारा 51 BNSS के अंतर्गत चिकित्सा जाँच या उसी अधिनियम की धारा 5 के अंतर्गत मजिस्ट्रेट के आदेश पर यह छूट लागू नहीं होती।
नार्को, पॉलीग्राफ और ब्रेन मैपिंग: सेल्वी बनाम कर्नाटक राज्य (5 मई 2010) में सुप्रीम कोर्ट ने कहा कि किसी भी व्यक्ति पर ये परीक्षण ज़बरदस्ती नहीं किए जा सकते, क्योंकि यह संविधान के अनुच्छेद 20(3) (स्वयं के विरुद्ध गवाह बनने के लिए बाध्य न किए जाने का अधिकार) और अनुच्छेद 21 का उल्लंघन है। सहमति से हुए परीक्षण का परिणाम भी स्वयं साक्ष्य नहीं है, लेकिन उसकी मदद से बाद में मिली वस्तु या जानकारी साक्ष्य अधिनियम की धारा 27 (अब धारा 23(2) BSA का परंतुक) के अनुसार साबित की जा सकती है। सहमति न्यायिक मजिस्ट्रेट के सामने दर्ज होनी चाहिए और वकील की मौजूदगी ज़रूरी है।
डीएनए और कस्टडी की कड़ी (chain of custody): कट्टवेल्लई बनाम तमिलनाडु राज्य (15 जुलाई 2025) में सुप्रीम कोर्ट ने दोषसिद्धि और मृत्युदंड दोनों रद्द करके अपीलकर्ता को रिहा करने का आदेश दिया, और कहा कि डीएनए साक्ष्य तभी भरोसेमंद है जब नमूने ठीक से लिए, सील किए, रखे और भेजे गए हों। अदालत ने निर्देश दिया कि नमूने एकत्र करने के 48 घंटे के भीतर प्रयोगशाला पहुँचें, ट्रायल कोर्ट की अनुमति के बिना पैकेट खोला या दोबारा सील न किया जाए, और संग्रह से लेकर दोषसिद्धि या बरी होने तक हर गतिविधि एक चेन ऑफ़ कस्टडी रजिस्टर में दर्ज हो, जो ट्रायल कोर्ट के रिकॉर्ड का हिस्सा होगा।
इलेक्ट्रॉनिक साक्ष्य: धारा 63 BSA (पहले धारा 65B) के अनुसार कंप्यूटर आउटपुट के साथ हर बार निर्धारित प्रमाणपत्र देना होता है।
Frequently asked questions
Forensic science is the use of scientific examination to answer questions in an investigation or trial: whose blood or DNA was found, whether a death was caused by poison, which gun fired a bullet, who wrote a document. No Indian statute defines it. Its results reach the court as the opinion of a person “specially skilled” in science or “any other field”, a relevant fact under Section 39 BSA (formerly Section 45 Evidence Act), and the BNSS adds duties to collect it, such as the forensic expert’s visit to the scene under Section 176(3).
The usual types are biological and DNA evidence (blood, semen, swabs, hair, nail clippings), fingerprints and other body “measurements”, chemical and toxicological evidence (poison, drugs), ballistics and explosives, questioned documents and handwriting, medical and post-mortem evidence, digital evidence, and psychiatric opinion. Laboratories are organised on similar lines; Himachal Pradesh’s Directorate of Forensics Services, for example, has divisions of Biology and Serology, Chemistry and Toxicology, Documents and Photography, Physics and Ballistics, DNA and Forensic Psychology, and Digital Forensics and Forensic Auditing facilities. In court each type is proved through Section 39 BSA or a report under Section 329 BNSS.
Yes. Under Section 39 BSA (formerly Section 45 Evidence Act) the opinion of experts on science, art, foreign law, “any other field”, handwriting and finger impressions is a relevant fact, and under Section 45 BSA its grounds are also relevant. Reports of the Government scientific experts listed in Section 329 BNSS (formerly Section 293 CrPC) “may be used as evidence” without calling the scientist. Admissibility is only the first step: the court then decides how much weight the evidence deserves, looking at its reliability and at how the samples were handled.
Section 45 of the Indian Evidence Act, 1872 made relevant the opinions of persons specially skilled in foreign law, science or art, or in questions of identity of handwriting or finger impressions. From 1 July 2024 the corresponding provision is Section 39(1) of the Bharatiya Sakshya Adhiniyam, 2023, which adds the words “or any other field”. Section 45A (Examiner of Electronic Evidence) is now Section 39(2) BSA. In the firm’s reading, judgments under Section 45 remain useful because its words were kept.
Yes, if it is by a Government scientific expert listed in Section 329(4) BNSS (formerly Section 293 CrPC), such as a Chemical Examiner, the Director of the Finger Print Bureau, the Director, Deputy Director or Assistant Director of a Central or State Forensic Science Laboratory, the Serologist to the Government, or a notified expert. The court “may, if it thinks fit, summon and examine” the expert, and if a party disputes the report under Section 330 BNSS the expert should be called. In Irfan v. State of M.P. (2025) a trial was vitiated because the DNA scientists were not examined.
No. In Ramesh Chandra Agrawal v. Regency Hospital Ltd. (11 September 2009) the Supreme Court said that “An expert is not a witness of fact and his evidence is really of an advisory character”, and that it is “not the province of the expert to act as Judge or Jury”. The expert must give the court the materials and reasons so that the judge can form an independent opinion. A tested opinion with clear data can carry great weight, but it is weighed with the rest of the evidence.
Among the most cited are Selvi v. State of Karnataka (5 May 2010) on narco-analysis, polygraph and brain-mapping tests; Ramesh Chandra Agrawal v. Regency Hospital (2009) on who is an expert and why expert evidence is advisory; Irfan v. State of M.P. (16 January 2025) on the accused’s right to examine the scientists behind a DNA report; Kattavellai @ Devakar v. State of Tamil Nadu (15 July 2025) on DNA and the chain of custody, with four directions; and Arjun Panditrao Khotkar ([2020] 7 SCR 180) on the electronic record certificate.
DNA profiling compares genetic material from samples such as blood, semen, swabs or hair with that of a known person. The Explanation to Section 51 BNSS expressly includes “DNA profiling” in the medical examination of an arrested accused. DNA evidence is not automatically conclusive: in Kattavellai (2025) the Supreme Court said a DNA profile “is valid and reliable, but the same depends on quality control and procedures in the laboratory”, that procedures outside the laboratory matter “equally”, and that DNA is “only of probative value, subject to the condition that it is properly dealt with”.
Chain of custody is the record of who collected, sealed, held, moved and examined an item, from the scene to the end of the trial. For DNA, the Supreme Court in Kattavellai (15 July 2025) directed documented collection, delivery to the laboratory “not later than 48-hours” (or reasons in the case diary), no opening or resealing without the trial court’s permission, and a Chain of Custody Register “appended as part of the Trial Court record”. The BNSS adds video-recording of searches and seizures (Section 105) and the sequence of custody of electronic devices in the police report (Section 193(3)).
As described in Selvi v. State of Karnataka (5 May 2010), a polygraph measures “changes in aspects such as respiration, blood pressure, blood flow, pulse and galvanic skin resistance” while the subject answers questions. Selvi held that “no individual should be forcibly subjected” to polygraph, narco-analysis or brain-mapping (BEAP) tests, as compulsion violates Articles 20(3) and 21. Even with consent, “the test results by themselves cannot be admitted as evidence”; only facts later discovered with their help can be proved (now the proviso to Section 23(2) BSA), and the NHRC safeguards apply.
Yes, within limits. Section 51 BNSS (formerly Section 53 CrPC) lets a registered medical practitioner, at police request, examine an arrested accused, including blood, semen, hair and DNA profiling, with reasonably necessary force; a woman is examined only by or under a female doctor. Section 349 BNSS lets a Magistrate order specimen signatures, finger impressions, handwriting or a voice sample. Selvi treated bodily substances as “material evidence”, outside Article 20(3). Under Section 3 of the Criminal Procedure (Identification) Act, 2022, a person arrested for an offence that is not against a woman or child and not punishable with seven years or more “may not be obliged” to give biological samples under that section, but this does not limit Section 51 BNSS or a Magistrate’s order under Section 5 of that Act.
For offences punishable with seven years or more, Section 176(3) BNSS says the officer in charge of the police station “shall … cause the forensic expert to visit the crime scene to collect forensic evidence” and have the process video-recorded on a mobile phone or other device. The duty applies “from such date, as may be notified within a period of five years by the State Government”, so it depends on the State’s notification. Where a State lacks a facility, it must notify the use of another State’s facility until its own is ready.
The main ones are Section 176(3) (forensic expert at the scene), Sections 105 and 185(2) (video-recording of search and seizure), Sections 51–53 (medical examination of the accused, including DNA profiling), Section 184 (examination of a rape survivor with her consent), Section 194 (inquest and post-mortem), Section 193(3) (sequence of custody of electronic devices), Sections 326, 328 and 329 (medical depositions and reports of Government experts), Section 330 (admitting or denying documents) and Section 349 (specimens and voice samples).
Section 39 BSA names “identity of handwriting or finger impressions” as a subject of expert opinion, and Section 72 BSA lets the court itself compare a disputed signature, writing or finger impression with one admitted or proved. Under Section 349 BNSS (formerly Section 311A CrPC) a Magistrate can order any person to give specimen signatures, finger impressions, handwriting or a voice sample, now even without arrest for recorded reasons. Finger Print Bureau reports are covered by Section 329(4)(c) BNSS, and a Ministry of Home Affairs release of 4 December 2024 says the NCRB has implemented the National Automated Fingerprint Identification System.
Phones, computers and storage media are examined by digital forensic units, and the opinion of an Examiner of Electronic Evidence notified under Section 79A of the IT Act is a relevant fact under Section 39(2) BSA. The electronic record itself is proved under Section 63 BSA (formerly Section 65B) with a certificate submitted “along with the electronic record at each instance”, signed by the person in charge of the device “and an expert”. The police report must state the sequence of custody of electronic devices (Section 193(3) BNSS).
Yes. In Kattavellai (2025) the Supreme Court noted that “many persons wrongly convicted have finally had justice served, with them being declared innocent because of advancements in this technology”, and in that case it set aside a death-sentence conviction, finding the DNA evidence “unusable” among other failures of proof. A conviction can be challenged in appeal, and the appellate court can reject unreliable evidence or, as in Irfan (2025), send the case back for the experts to be examined. On compensation, the Court recalled that a clean acquittal after very long incarceration “may give rise to a claim for compensation” under Article 21 (V. Senthil Balaji, 2024), and said that “it is for the legislature to consider this aspect”.
Biological samples can be contaminated or degrade, and the longer and less documented their journey, the harder it is to rule out tampering. As described in Kattavellai (2025), the Supreme Court rejected DNA evidence in Manoj v. State of M.P. because the recovery was from an open place and contamination could not be ruled out, in Rahul because samples lay in the police Malkhana for two months, and in Prakash Nishad because of unexplained delay in sending samples to the laboratory. In Kattavellai the swabs reached the laboratory after 41 days, without explanation.
Section 329 BNSS does not mention accreditation; it applies to reports of the Government scientific experts it lists and to experts notified by the Central or State Government. In the firm’s reading, a report from a laboratory outside Sections 328 and 329 is not covered by them, so if the other side disputes it, it has to be proved in the ordinary way, normally by examining its author (Section 55 BSA); if its genuineness is not disputed, Section 330(3) BNSS allows it to be read in evidence without proof of the signature. Whatever the source, expert evidence must be “based on reliable principles” from a person “qualified in that discipline” (Ramesh Chandra Agrawal, 2009), and in Kattavellai (2025) the Supreme Court found “no uniformity” in DNA procedures across agencies.
The main ones are: no compulsory narco, polygraph or brain-mapping tests (Selvi, 2010, under Articles 20(3) and 21); examination of a woman accused only by or under a female doctor (Section 51(2) BNSS); no medical examination of a rape survivor without her consent or that of a person competent to consent for her (Section 184(7) BNSS); under Section 3 of the Criminal Procedure (Identification) Act, 2022, a person arrested for an offence that is not against a woman or child and not punishable with seven years or more “may not be obliged” to give biological samples under that section (this does not limit a medical examination under Section 51 BNSS or a Magistrate’s order under Section 5 of the 2022 Act); destruction of the measurements of an unconvicted person who is released without trial, discharged or acquitted, after all legal remedies are exhausted, unless the court directs otherwise (Section 4(2)); and video-recording of searches and seizures (Section 105 BNSS).
Direct evidence is a witness’s account of the fact in issue itself, such as an eyewitness to the act. (Section 55 BSA, which requires oral evidence to be “direct”, is a different rule: it means first-hand, not hearsay.) A DNA match or fingerprint is usually circumstantial: it proves a fact from which another is inferred. Where there is no eyewitness, as in Kattavellai (2025), the chain of circumstances must point to the guilt of the accused alone. Because expert opinion is “of an advisory character” and DNA is “only of probative value”, courts weigh forensic evidence with everything else, and one unreliable forensic link can break the chain.
Daubert v. Merrell Dow Pharmaceuticals (1993) is a United States Supreme Court decision; the Supreme Court of India described it in Selvi (2010) as asking whether a technique has been tested and peer-reviewed, its error rate, its standards and its scientific acceptance. Indian law has no statutory Daubert test. Under Section 39 BSA the expert must be in “a recognized field of expertise”, the evidence “based on reliable principles” and the expert “qualified in that discipline” (Ramesh Chandra Agrawal, 2009); weaknesses are exposed through the grounds of the opinion (Section 45 BSA) and cross-examination.
Yes. Illustration (b) to Section 39 BSA deals with exactly this: where the question is whether a person, by reason of unsoundness of mind, was incapable of knowing the nature of his act or that it was wrong or contrary to law, the opinions of experts on whether his symptoms “commonly show unsoundness of mind” are relevant. Himachal Pradesh’s forensic directorate, for example, has a Forensic Psychology division. The court decides the question itself on all the evidence.
A post-mortem report records a doctor’s examination of a body to find the cause of death. Under Section 194(3) BNSS (formerly Section 174 CrPC) the police must send the body to the nearest Civil Surgeon or other qualified medical person in specified cases, including any case of doubt about the cause of death. The doctor’s opinion is expert evidence under Section 39 BSA; under Section 326 BNSS a medical witness’s deposition taken by a Magistrate in the accused’s presence can be read in evidence, and the court may, and on application shall, summon the doctor.
विशेषज्ञ की राय भारतीय साक्ष्य अधिनियम, 2023 (BSA) की धारा 39 में है, जो पुराने भारतीय साक्ष्य अधिनियम, 1872 की धारा 45 की जगह आई है। इसमें विदेशी कानून, विज्ञान, कला, लिखावट और उंगलियों के निशान के साथ “किसी अन्य क्षेत्र” (any other field) के विशेषज्ञों की राय भी प्रासंगिक मानी गई है। सरकारी फॉरेंसिक प्रयोगशाला की रिपोर्ट धारा 329 BNSS (पहले धारा 293 CrPC) के अंतर्गत बिना वैज्ञानिक को बुलाए साक्ष्य में पढ़ी जा सकती है, पर अदालत उसे बुला सकती है। (यह फर्म का हिंदी सारांश है।)
भारतीय साक्ष्य अधिनियम, 2023 चे कलम 39 हे जुन्या पुरावा कायद्याच्या कलम 45 ची जागा घेते. जुन्या कलमात परदेशी कायदा, विज्ञान, कला, हस्ताक्षर आणि बोटांचे ठसे यांवरील तज्ज्ञांचे मत संबंधित (relevant) मानले जात असे. नव्या कलम 39(1) मध्ये “or any other field” (इतर कोणतेही क्षेत्र) हे शब्द जोडले आहेत, त्यामुळे तज्ज्ञांची व्याप्ती वाढली आहे. कलम 39(2) नुसार इलेक्ट्रॉनिक पुराव्यावर IT कायद्याच्या कलम 79A खालील Examiner of Electronic Evidence चे मतही संबंधित आहे. (हा फर्मचा मराठी सारांश आहे; अधिकृत मराठी पाठ वापरलेला नाही.)
Conclusion
Forensic evidence enters an Indian criminal trial as expert opinion under Section 39 BSA, which replaced Section 45 of the Evidence Act and widened it to “any other field”, or as a report of a listed Government scientific expert under Section 329 BNSS, which replaced Section 293 CrPC. The new procedure code also strengthens collection: forensic experts at the scene of serious offences once States notify Section 176(3), video-recording of searches and seizures under Section 105, and a recorded sequence of custody for electronic devices.
The Supreme Court’s message is consistent: expert evidence is advisory, its grounds and data must be open to testing, nobody can be forced into narco or polygraph tests, and even DNA is only as strong as the chain of custody behind it. The 2025 directions in Kattavellai, requiring a Chain of Custody Register in every DNA case, and the insistence in Irfan on examining the scientists behind a DNA report, mean that both prosecution and defence must now look as closely at how evidence was handled as at what the laboratory found.
Sources used for this post: the Bharatiya Sakshya Adhiniyam, 2023 (Act 47 of 2023), Sections 2(1)(d), (e) and (f), 23, 39, 40, 41, 45, 55, 63, 72 and 170 (India Code, as on 6 October 2025); the Bharatiya Nagarik Suraksha Sanhita, 2023 (Act 46 of 2023), Sections 2(1)(a), 51, 52, 53, 105, 176, 184, 185, 193, 194, 326, 328, 329, 330, 349 and 531 (India Code, as on 6 October 2025); the Criminal Procedure (Identification) Act, 2022 (Act 11 of 2022), Sections 1–6 and 10, in force from 4 August 2022 by notification S.O. 3653(E) of 3 August 2022 (India Code, as on 6 October 2025); the Constitution of India, Articles 20(3) and 21 (Legislative Department, English edition of 2026); the firm’s Gazette-checked comparison data for the old Evidence Act, CrPC and IPC sections; the Supreme Court’s official copies of Smt. Selvi v. State of Karnataka, Criminal Appeal No. 1267 of 2004, 5 May 2010 (https://api.sci.gov.in/jonew/judis/36303.pdf), Ramesh Chandra Agrawal v. Regency Hospital Ltd., Civil Appeal No. 5991 of 2002, 11 September 2009 (https://api.sci.gov.in/jonew/judis/35479.pdf), Irfan alias Bhayu Mevati v. State of Madhya Pradesh, Criminal Appeal Nos. 1667–1668 of 2021, 2025 INSC 150, 16 January 2025 (https://api.sci.gov.in/supremecourt/2021/29948/29948_2021_6_105_58516_Judgement_16-Jan-2025.pdf) and Kattavellai @ Devakar v. State of Tamil Nadu, Criminal Appeal No. 1672 of 2019, 2025 INSC 845, 15 July 2025 (https://api.sci.gov.in/supremecourt/2019/35590/35590_2019_13_1501_62329_Judgement_15-Jul-2025.pdf), including its descriptions of Anil v. State of Maharashtra, Manoj v. State of M.P., Rahul and Prakash Nishad v. State of Maharashtra and its extract from V. Senthil Balaji v. Deputy Director, Directorate of Enforcement (2024 INSC 739); the Digital Supreme Court Reports headnote of Arjun Panditrao Khotkar v. Kailash Kushanrao Gorantyal, [2020] 7 SCR 180 (https://digiscr.sci.gov.in/view_judgment?id=MTA2MjI%3D); the Directorate of Forensics Services, Government of Himachal Pradesh (https://himachal.nic.in/forensics/); the Bureau of Police Research and Development’s table of State notifications under the BNSS (Table B, https://bprd.nic.in/page/table_b, last updated 19 October 2026); and the Press Information Bureau release of the Ministry of Home Affairs of 4 December 2024 on NAFIS (https://www.pib.gov.in/PressReleseDetailm.aspx?PRID=2080660®=48&lang=2).
