In trials witnesses often slant their testimony to advance their interests. To obtain truthful testimony, courts rely on perjury rules. We show that perjury rules are not truth-revealing and we derive a truth-revealing mechanism for the same set of restrictions under which perjury rules operate. If the judge uses a truth-revealing mechanism, he will get less testimony than under perjury because the defendant will not present a witness with unfavorable news; however, testimony is of higher quality. We show that a court striving for precision prefers truth-revelation to perjury. If the court is rational in the Bayesian sense, chances for the defendant to prevail are the same under perjury and truth-revelation from an ex ante point of view. Truth-revelation thus dominates perjury even when the lower quantity of testimony is taken into account.