Credibility refes to the reliability of testimony, based on competence of the witness and likelihood that it is true. It may also refer to someone's reputation for truthfulness. Credibility of testimony is usually supported by other substantiating evidence, but credibility is often a subjective determination to be made by the trier of fact (judge or jury). In general, the rules of evidence disallow character witnesses to be called to testify to a witness' reputation for truthfulness or untruthfulness unless such reputation for truthfulfulness or untruthfulness has already been attacked.
