The credit of a witness may be impeached in the following ways by the adverse party, or, with the consent of the Court, by the party who calls him—
(a) by the evidence of persons who testify that they, from their knowledge of the witness, believe him to be unworthy of credit;
(b) by proof that the witness has been bribed, or has accepted the offer of a bribe, or has received any other corrupt inducement to give his evidence;
(c) by proof of former statements inconsistent with any part of his evidence which is liable to be contradicted.
Explanation. — —A witness declaring another witness to be unworthy of credit may not, upon his examination-in-chief, give reasons for his belief, but he may be asked his reasons in cross-examination, and the answers which he gives cannot be contradicted, though, if they are false, he may afterwards be charged with giving false evidence.
Illustrations
(a) A sues B for the price of goods sold and delivered to B. C says that he delivered the goods to B. Evidence is offered to show that, on a previous occasion, he said that he had not delivered goods to B. The evidence is admissible.
(b) A is accused of the murder of B. C says that B, when dying, declared that A had given B the wound of which he died. Evidence is offered to show that, on a previous occasion, C said that B, when dying, did not declare that A had given B the wound of which he died. The evidence is admissible.
Legal Commentary & Landmark Judgments: Section 158
Section 158 provides the statutory modes of impeaching the credit of a witness, allowing the adverse party or the calling party (with court leave) to prove unworthiness of credit, corrupt inducement, or previous inconsistent statements.
In cross-examination, focus on material contradictions between the witness's deposition and their first police or regulatory statement. If you prove the witness received financial benefits from the opponent, credit is shattered under Section 158.