Perjury versus Truth-Revelation: Quantity or Quality of Testimony

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.litigation process; witness; truth-revelation; mechanism design; perjury rule