R v B (KG), [1993] 1 SCR 740, popularly known as the KGB case, is a leading Supreme Court of Canada decision on the admissibility of prior inconsistent statements as proof of the truth of their contents. Prior to this case, prior inconsistent statements made by a witness other than an accused could merely be used to impeach the witness's credibility, not for substantive purposes. Here, the Court held that if the statements could be found to be both necessary and reliable then the statements could be admitted as an exception to the hearsay rule.