pardon, in law, exemption from punishment for a criminal conviction granted by the grace of the executive of a government. A general pardon to a class of persons guilty of the same offense (e.g., insurrection) is an amnesty. A pardon (at least in the United States) absolutely terminates criminal liability, including any restrictions that result from a criminal conviction (though the pardoned person is not exonerated from the civil liability that a crime may have incurred). A pardon is thus to be distinguished from alleviation of punishment (such as commutation of sentence, reprieve, and parole), which does not nullify the conviction and all of its effects. The Constitution of the United States gives the president power to grant reprieves and pardons for all federal crimes, but he may not release a person from the effects of impeachment; pardons issued by the president are unreviewable. In most of the states the governor has nearly the same power in respect to state crimes. Usually, the governor may not pardon those convicted of treason or criminal contempt of court. In canon law the pardon is the absolution granted in penance; in the Middle Ages the word was used commonly to mean an indulgence (hence pardoner, a dispenser of indulgences).