Bharatiya Sakshya Adhiniyam, 2023
Section 40
Facts bearing upon opinions of experts
Facts, not otherwise relevant, are relevant if they support or are inconsistent with the opinions of experts, when such opinions are relevant. Illustrations.
(a) The question is, whether A was poisoned by a certain poison. The fact that other persons, who were poisoned by that poison, exhibited certain symptoms which experts affirm or deny to be the symptoms of that poison, is relevant.
(b) The question is, whether an obstruction to a harbour is caused by a certain sea-wall. The fact that other harbours similarly situated in other respects, but where there were no such sea-walls, began to be obstructed at about the same time, is relevant.
Why this exists
Expert opinions (like a doctor's view on poisoning symptoms or an engineer's view on harbour silting) can be hard for judges to test on their own. This provision, carried over from the Indian Evidence Act's Section 46, recognizes that comparative or corroborating facts—cases with similar patterns—can help a court judge whether an expert's opinion is reliable or shaky, even though those facts wouldn't independently be relevant to the dispute.
How courts read it
Courts have consistently treated this as a natural extension of the rules on expert evidence: once an expert's opinion is admissible, any fact that logically supports or contradicts that opinion also becomes admissible, even if it involves third parties or separate incidents. Indian courts under the old Section 46 used this to allow comparative medical or scientific data (such as symptoms in other poisoning victims or behavior of similar structures) as a check on expert testimony, rather than accepting expert opinions at face value.
Common misconceptions
- Myth: This provision lets courts bring in any random fact to argue against an expert.
Fact: The fact must specifically support or contradict the expert opinion already relevant to the case—it can't be unrelated or speculative. - Myth: Only the side using the expert can rely on this provision.
Fact: Either side can use comparative facts—whether to strengthen or to challenge an expert's opinion.