Canadian Criminal Evidence/Credibility/Bias, Interest, and Corruption

General Principles
A witness can be questioned on their truthfulness due to bias or lack of impartiality. This includes questions that show hate, malice, affection or fear. If the witness denies circumstances showing bias, then the party may call evidence to contradict it.

Bias or interest only goes to credibility when the bias or interest can cause a witness to lie or exaggerate the truth to harm an opposing party or benefit their preferred party. Bias alone is not sufficient.

Where a witness denies bias, it is permissible to call contradictory evidence to prove it. However, if the defendant calls evidence to contradict a denial of bias, the crown has the right to call evidence to rehabilitate the witness.

A witness can be asked about their communications with other witnesses before trial to suggest bias or interest.

Doctrine of Recent Complaints
The common law doctrine of recent complaints permits the judge to make an adverse finding against credibility.

Section 275 removes this doctrine for certain offences sex offences: