(a) The question is, whether A was poisoned by a certain poison.
The fact that other persons, who were poisoned by that person, 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 harbor 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, are relevant.
Section 46 lays down the principles that when the opinion of experts is relevant, any fact which is otherwise irrelevant will become relevant if it either supports or contradicts the opinion of experts. When an opinion of the experts is cited and declared to be relevant the parties have right to produce additional evidences to support or rebut the opinion of the experts. For example— ‘A’ was poisoned by a certain poison. A medical expert established that the certain type of poison resulted in death of ‘A’.
Evidence may be given to that effect that other persons were also administered poison by that person, exhibited symptoms which the medical expert affirms or denies to the symptom of that person, is relevant.
Thus, where the opinion of an expert is contradicted the evidences of outstanding qualities may be allowed to be produced. In State of Haryana v Bagirath it was held that the court is not bound by the opinion of the medical expert, but has to form its own opinion. In this case, the medical witness ruled out the possibility of two successive blows by a sharp weapon falling at the same time. The court rejected this opinion and accepted the prosecution version. Where there is some variance between the medical evidence and the evidence of an eye witness, the court should not take the easy way of giving benefit of doubt to the accused. It is treated that where the eye-witnesses account is found credible and trustworthy medical opinion pointing to alternative possibilities is not accepted as conclusive.