Adversarial versus inquisitorial testimony

Abstract

An arbiter has to decide a case under a purely adversarial procedure. He can do so using his priors, or the two parties to the conflict may present further evidence. The parties can distort the evidence in their favor at a cost. In equilibrium the two parties never testify together. When the evidence is much in favor of one party, this party testifies; the testimony is, however, distorted. When the evidence is close to the prior mean, no party testifies. We compare this result with the outcome under a purely inquisitorial procedure where the arbiter decides how much testimony he wants to hear.