Plea Bargaining and Prosecutorial Discretion

A model of plea bargaining with asymmetric information is presented. The prosecutor's private information consists of the strength of the case, while the defendant's private information is his or her own guilt or innocence. A sequential equilibrium is computed, in which a fraction of cases are dismissed because they are too likely to involve an innocent defendant; in the remaining cases, the prosecutor's offer of a sentence in exchange for a plea of guilty signals the strength of the case. I then ask whether the prosecutor (and society) might be better off if constrained to make the same offer to all defendants, regardless of the strength of the case. It is shown that, depending upon other features of the criminal justice system and upon the preferences of society, either of these regimes may be preferred to the other. In particular, it is possible that unlimited discretion is disadvantageous for the prosecution (since it carries with it the requirement of sequential rationality).