Plea bargaining in the United States

Plea bargaining in the United States is very common; the vast majority of criminal cases in the United States are settled by plea bargain rather than by a jury trial.^[1] They have also been increasing in frequency—they rose from 84% of federal cases in 1984 to 94% by 2001.^[2] Plea bargains are subject to the approval of the court, and different States and jurisdictions have different rules. Game theory has been used to analyze the plea bargaining decision.^[3]

The constitutionality of plea bargaining was established by Brady v. United States in 1970,^[4] although the Supreme Court warned that plea incentives which were sufficiently large or coercive as to over-rule defendants' abilities to act freely, or used in a manner giving rise to a significant number of innocent people pleading guilty, might be prohibited or lead to concerns over constitutionality.^[5] Santobello v. New York added that when plea bargains are broken, legal remedies exist.^[6]

Several features of the American justice system tend to promote plea bargaining. The adversarial nature of the system puts judges in a passive role, in which they are completely dependent upon the parties to develop the factual record and cannot independently discover information with which to assess the strength of the case against the defendant. The parties thus can control the outcome of the case by exercising their rights or bargaining them away. The lack of compulsory prosecution also gives prosecutors greater discretion. And the inability of crime victims to mount a private prosecution and their limited ability to influence plea agreements also tends to encourage plea bargaining.^[7] These inducements to plea bargaining have been described as a "trial penalty",^[8] and prosecutors have been described as monopsonists.^[9]