Truth-Revealing Mechanisms for Courts

In trials witnesses often slant their testimony in order to advance their own interests. To obtain truthful testimony, the law relies on cross-examination under threat of prosecution for perjury. We show that perjury law is an imperfect truthrevealing mechanism. Moreover, we develop a truth-revealingmechanism for the same set of restrictions under which perjury rules operate. Under this mechanism the witness is sanctioned if a court eventually finds that the testimony was incorrect; the court need not determine that testimony was dishonest. We explain how truth-revealing mechanisms could combat distortions of observations by factual witnesses and exaggerations by experts, including "junk science".