Unreliable witnesses are often referred to as LIARS, which is the five-letter solution to this crossword. Unreliable witnesses are individuals who cannot be trusted to provide accurate or truthful testimony in a court of law. They may have a vested interest in the outcome of a case, or they may simply be untrustworthy due to their character or past behavior. In any case, their testimony is not considered reliable and is often disregarded by the court.