Adversarial versus Inquisitorial Testimony

Winand Emons,Claude Fluet

doi:10.3917/reco.713.0429

Abstract

Un arbitre doit décider d’un litige entre deux parties dans le cadre d’une procédure purement accusatoire. Sa décision peut reposer uniquement sur ses a priori, en l’absence d’information supplémentaire ; ou bien elle peut reposer sur les éléments de preuve additionnels soumis volontairement par les parties au litige. Lorsqu’elle décide de témoigner, et moyennant un coût, chaque partie peut déformer la réalité en sa faveur. À l’équilibre, les parties ne témoignent jamais simultanément. Une partie ne témoigne que si les faits sont suffisamment en sa faveur, mais son témoignage présente alors une version exagérée de cet avantage. Inversement, si les faits sont proches de l’évaluation a priori du décideur, aucune des parties ne témoigne. Nous comparons cet équilibre à celui qui serait obtenu avec une procédure purement inquisitoire où c’est l’arbitre qui décide du nombre de témoignages.

Highlights

How much testimony will an arbiter hear in adversarial proceedings when the parties to the conflict may spend resources to misrepresent evidence in their favor? Will both parties come forward with boosted claims offsetting each other, or will only the party for whom the evidence is favorable testify? Are there circumstances where no party testifies? What are the efficiency properties of the outcome? Is the adversarial procedure where the parties to the conflict decide whether or not they testify better than the inquisitorial procedure where the arbiter decides how much testimony he wants to hear? In this paper we address these questions.An arbiter has to decide on an issue which we take to be a real number, for example, the damages that one party owes to the other
Our paper is most closely related to the economics literature comparing adversarial with inquisitorial procedures of truth-finding
Let us compare our least-cost equilibrium under the adversarial procedure with the least-cost equilibrium under the inquisitorial procedure which we derive in Emons and Fluet (2009)

Summary

Introduction

When the arbiter decides to hear no party, he rationally adjudicates the prior mean; there is no falsification but error costs are positive. If incorrect decisions do not matter too much and the fixed cost of testifying is sufficiently large, the adversarial procedure is better than the inquisitorial one. Our paper is most closely related to the economics literature comparing adversarial with inquisitorial procedures of truth-finding In this literature, “inquisitorial” usually refers to a system where a neutral investigator searches for evidence, “adversarial” to one where the parties to the conflict control the uncovering and presentation of evidence; see Shin (1998), Dewatripont and Tirole (1999), Froeb and Kobayashi (2001), and Palumbo (2001).

The Model

The least-cost equilibrium

Comparing the adversarial with the inquisitorial procedure

Concluding Remarks