Traditionally, parole boards have played a major role in releasing offenders from prisons. Each state has its own parole board whose members are appointed by the governor. The parole board is usually one component of a large parole agency that supplies post-prison supervision to offenders after they are released from prison. The point at which a prisoner is eligible for parole is a matter of state law, so there is considerable variation among the states.

In a sentencing system in which the judge only specifies a maximum sentence, the prisoner might, for example, become eligible for parole after serving one-third of the sentence. Members of the parole board typically hold brief interviews with the prospective parolees at the prison. The board is generally interested in the prisoner's adjustment within the prison, but it will invariably consider the facts of the crime and the prisoner's previous criminal record.

Finally, the governor of each state has the power to pardon or commute the sentences of offenders in that state. The president of the United States has similar authority for federal offenders. Frequently, the law provides for the appointment of a pardon board, which sifts through petitions, conducts investigations and makes affirmative recommendations to the chief executive. Governors, especially in the most prolific death sentencing states, are frequently called upon to commute death sentences. Unlike in many countries, general amnesties are not a part of American law nor tradition.