Section 45 Evidence Act vs Section 39 BSA — Expert Opinion

Quick Answer

Section 45 of the Indian Evidence Act, 1872 has been replaced by Section 39 of the Bharatiya Sakshya Adhiniyam, 2023 (BSA). The new provision makes two significant expansions. First, Section 39(1) adds "any other field" to the enumerated categories of science, art, handwriting, finger impressions, and foreign law — allowing courts to admit expert opinion from any recognised domain of specialised knowledge. Second, Section 39(2) creates a dedicated sub-section for electronic evidence experts, formally recognising the Examiner of Electronic Evidence referred to in Section 79A of the Information Technology Act, 2000, and deeming such examiners to be "experts" for evidentiary purposes. This absorbs the old Section 45A (added by the IT Act amendment) into the main expert opinion framework.

What Changed

Full Statutory Text

Section 45, Evidence Act

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 are relevant facts. Such persons are called experts.

Section 45A, Evidence Act (added by IT Act 2000)

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 is a relevant fact.

Section 39, BSA

(1) 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 on any other field, are relevant facts. Such persons are called experts.

(2) 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, is a relevant fact.

Explanation. — For the purposes of this sub-section, an Examiner of Electronic Evidence shall be an expert.

Key Differences

1. "Any other field" — catch-all expansion. Section 39(1) BSA adds the phrase "or on any other field" after the traditional enumeration of foreign law, science, art, handwriting, and finger impressions. This is a significant expansion. Under the old Section 45, parties seeking to adduce expert opinion in non-traditional fields — such as data science, artificial intelligence, behavioural psychology, environmental science, forensic accounting, or blockchain technology — had to argue that these fell within "science" or "art." The BSA eliminates this interpretive stretch by creating a statutory basis for expert opinion in any field of specialised knowledge.

2. Integration of electronic evidence expertise. Section 45A of the Evidence Act existed as a standalone provision introduced by the IT Act amendment. The BSA absorbs this into Section 39(2), creating a unified expert opinion framework. The Explanation to Section 39(2) expressly declares that an Examiner of Electronic Evidence "shall be an expert" — removing any doubt about their status.

3. Structural clarity. The two-sub-section structure (general expert opinion in 39(1), electronic evidence expert in 39(2)) provides clear demarcation. This is practically useful: courts and practitioners can cite Section 39(1) for traditional experts and Section 39(2) specifically for electronic evidence matters.

4. No change to advisory nature. Neither the Evidence Act nor the BSA elevates expert opinion to binding proof. Courts continue to treat expert evidence as opinion evidence — relevant but not conclusive. The judge retains full discretion to accept, reject, or partially accept expert testimony based on reasoning, methodology, consistency, and corroborative evidence.

5. Examiner of Electronic Evidence given express "expert" status. The Evidence Act's Section 45A made the Examiner's opinion a "relevant fact" but did not expressly call the Examiner an "expert." The BSA's Explanation to Section 39(2) closes this gap, ensuring that all procedural protections and standards applicable to expert witnesses apply equally to electronic evidence examiners.

What This Means for Practitioners

The "any other field" expansion is the most practically significant change. It opens several new possibilities:

Forensic accounting and valuation experts. In corporate fraud, insolvency, and securities enforcement cases, forensic accountants and business valuation experts can now be admitted under a direct statutory basis rather than arguing they practice "science" or "art."

Digital forensics and cybersecurity experts. Beyond the formal Examiner of Electronic Evidence under Section 39(2), private-sector cybersecurity experts, digital forensic analysts, and data recovery specialists can be admitted under Section 39(1) as experts in "any other field."

AI and machine learning specialists. As AI-generated evidence becomes more common (deepfakes, AI-assisted document analysis, algorithmic decision-making), experts in artificial intelligence can now opine on the reliability, methodology, and limitations of such systems.

Practitioners should note: The expansion of eligible expert fields does not lower the standard for qualifying as an expert. The witness must still be "specially skilled" in the relevant field. Courts will continue to assess qualifications, experience, methodology, and credibility before admitting expert testimony. The BSA's change merely expands the range of fields — not the threshold of expertise.

For electronic evidence, the combination of Section 39(2) (expert opinion) and Section 63 (admissibility certificate with hash value) creates a two-layer authentication framework. The Section 63 certificate validates the integrity of the electronic record, while the Section 39(2) expert opines on its content and significance.

Does Old Case Law Still Apply?

Yes, substantially. The core principles governing expert evidence remain unchanged:

Ramesh Chandra Agrawal v. Regency Hospital (2009) 9 SCC 709 — The Supreme Court's principles for evaluating expert testimony (qualifications, methodology, reasoning, consistency with other evidence) remain the governing standard. The BSA's expansion of eligible fields does not alter how courts evaluate the quality of expert opinion.

State of H.P. v. Jai Lal (1999) 7 SCC 280 — Expert opinion is advisory, not binding. The court is the ultimate arbiter of fact and may disagree with even well-qualified experts if the opinion lacks logical foundation or conflicts with established facts. This principle continues unmodified.

Malay Kumar Ganguly v. Dr. Sukumar Mukherjee (2009) 9 SCC 221 — Medical negligence cases often turn on expert opinion. The principles developed for evaluating competing expert testimonies remain fully applicable under Section 39(1) BSA.

Case law under Section 45A (electronic evidence expert) carries over directly to Section 39(2) BSA, given the identical substantive language.

Judicial interpretation under BSA Section 39 (post-July 2024)

The following cases from the Veritect Legal Intelligence database show how courts are applying expert evidence principles in practice:

C. Kamalakkannan v. State of Tamil Nadu (3 March 2025)

Court: Supreme Court of India | Judges: Mehta, J.; Vikram Nath, J. | Result: Acquitted

The Supreme Court acquitted the accused in a case where the prosecution relied on expert opinion without adequate primary evidence of the disputed document. The Court held that expert opinion under Section 45 (now BSA Section 39) is redundant when the primary document it purports to analyse has not been independently proved. Expert evidence supplements primary evidence — it does not replace it. This reinforces the principle that expert opinion remains opinion evidence and cannot fill evidentiary gaps in the prosecution's case.

Veritect reference: Diary_21310-2020_Judgment

Kailas v. State of Maharashtra (15 September 2025)

Court: Supreme Court of India | Judge: Manoj Misra | Result: Re-trial order set aside

The Supreme Court set aside a High Court order directing re-trial where the prosecution's electronic evidence expert had not been required to replay the electronic record in court. The Court held that a certified electronic record is admissible under the relevant provisions without mandatory replay, and that an expert opinion on the electronic record's content and integrity (under BSA Section 39(2)) is sufficient when the record has been properly certified under Section 63 BSA. This clarifies the interplay between the electronic evidence expert under Section 39(2) and the Section 63 certificate framework.

Veritect reference: Diary_8941-2025_Judgment

Emerging patterns

1. Expert opinion cannot substitute for primary evidence. The 2025 SC decision in Kamalakkannan reinforces that expert analysis under Section 39 is supplementary — the underlying document or evidence must first be independently proved through proper channels.
2. Electronic evidence expert and Section 63 certificate are complementary. The Kailas decision clarifies that Section 39(2) expert opinion and Section 63 certification serve distinct purposes — the certificate validates integrity, the expert interprets content.
3. "Any other field" expansion remains untested. No post-2024 Supreme Court decision has yet interpreted the scope of the "any other field" language in Section 39(1) BSA. The first such decision will be significant for emerging disciplines like AI, forensic accounting, and blockchain analysis.

Frequently Asked Questions

Can any expert in any field now testify in court? The field must be one requiring specialised skill or knowledge beyond ordinary human experience, and the witness must be "specially skilled" in that field. The BSA's "any other field" language removes the limitation to enumerated categories but does not remove the requirement of demonstrated expertise.

Is the Examiner of Electronic Evidence the only person who can testify on electronic evidence? No. Section 39(2) specifically recognises the Examiner referred to in Section 79A of the IT Act, but private electronic evidence experts can also testify under Section 39(1) as persons specially skilled in "any other field." The Examiner enjoys a specific statutory recognition, but is not the exclusive expert.

Does expert opinion on electronic evidence replace the Section 63 certificate requirement? No. The Section 63 certificate addresses the admissibility and integrity of the electronic record itself. Expert opinion under Section 39(2) addresses the interpretation, analysis, and significance of the electronic evidence. Both may be required in complex cases — the certificate to get the evidence admitted, and the expert to help the court understand it.

Can courts reject expert opinion even under the expanded BSA framework? Yes. The advisory nature of expert evidence is unchanged. Courts are free to reject expert opinion if the methodology is flawed, the reasoning is circular, the opinion lacks factual foundation, or it is contradicted by more reliable evidence.