Optimal Decision Mechanisms for Committees: Acquitting the Guilty

TL;DR

This paper models decision-making in committees with biased agents, identifying optimal voting mechanisms that balance biases to improve collective judgments, applicable to juries, boards, and political bodies.

Contribution

It formulates the problem as a mechanism design challenge and derives the optimal voting rule when agents are biased, linking it to historical judicial procedures.

Findings

Optimal voting mechanisms depend on agents' bias levels.

The derived mechanism is a voting rule that balances convictions.

Application to ancient Jewish judicial procedures.

Abstract

A group of privately informed agents chooses between two alternatives. How should the decision rule be designed if agents are known to be biased in favor of one of the options? We address this question by considering the Condorcet Jury Setting as a mechanism design problem. Applications include the optimal decision mechanisms for boards of directors, political committees, and trial juries. While we allow for any kind of mechanism, the optimal mechanism is a voting mechanism. In the terminology of the trial jury example: When jurors (agents) are more eager to convict than the lawmaker (principal), then the defendant should be convicted if and only if neither too many nor too few jurors vote to convict. This kind of mechanism accords with a judicial procedure from ancient Jewish law.