In the Shadows: A Review of the Research on Plea Bargaining

The plea-bargaining process is largely informal, undocumented, and unchallenged. More than ninety percent of convictions are the result of guilty pleas instead of trials. Even a ten percent reduction in the number of guilty pleas would require the criminal justice system to double its judicial capacity. Before designing and implementing reforms, one must explore the small—but increasingly influential—body of empirical research on plea bargaining. Numerous factors influence the decision-making process: (1) coercive elements such as pre-trial detention and threats of onerous sentences; (2) case characteristics such as the severity of charges, defendants’ criminal history, and the strength of evidence against them; (3) demographic characteristics and associated systemic inequities; (4) organization, structure, and content of criminal codes; (5) heavy caseloads among prosecutors and pressure to hasten the disposal of cases; (6) differences in sentences received for those exercising their right to trial; and (7) defendants’ own perception of their innocence. These studies demonstrate that the magnitude of the average trial penalty differs between jurisdictions and offenses. Nevertheless, the trial penalty is significant, for sentences imposed at trial are on average sixty-four percent longer than those imposed through plea.

“Although there is evidence that most people receive more favorable sentencing outcomes through plea bargaining than they would if they had taken their cases to trial, the exact contours of how such bargains are reached, and the factors—whether individual, legal, institutional, or demographic—that ultimately play a key role in influencing plea outcomes remain both ambiguous and opaque.” p. 6–7