Canadian Law of Evidence/Credibility
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Credibility evidence comprises evidence admitted for the purposes of strengthening or weakening the testimony of a witness or an accused. Credibility evidence that is used to impeach a witness can be submitted at any point from the time the witness takes the stand. The rule is that a witness always puts their credibility at issue whenever they testify and so it is open to attack. Evidence that bolsters a witness's credibility, however, is not admittable until the credibility of that witness has been impeached.