We explore the notion of "verifiability" by analyzing a simple model of evidence production in contractual relationships with complete information. We characterize implementability in terms of the existence and form of "hard evidence." We provide results on maximal and minimal evidence production that are, respectively, necessary and sufficient for implementation. We briefly discuss the relevance of our results to actual legal institutions. (C) 2003 Elsevier Inc. All rights reserved.

This paper addresses how hard evidence can be incorporated into mechanism-design analysis. Two classes of models are compared: (a) ones in which evidentiary decisions are accounted for explicitly, and (b) ones in which the players make abstract declarations of their types. Conditions are provided under which versions of these models are equivalent. The paper also addresses whether dynamic mechanisms are required for Nash implementation in settings with hard evidence. The paper shows that static mechanisms suffice in the setting of "evidentiary normality" and that, in a more general environment, one can restrict attention to a class of three-stage dynamic mechanisms.