What can a presidential pardon actually do?

The Constitution gives the president power to grant reprieves and pardons for offenses against the United States, except in cases of impeachment. That covers federal crimes only. A pardon can be issued after conviction, before conviction, or even before charges, as Ford's pardon of Nixon demonstrated, and it can be conditional, partial, or extended to a class of people, as with Carter's amnesty for Vietnam-era draft evaders. Related powers include commutation, which reduces a sentence without erasing the conviction, and remission of fines.

The limits are structural rather than discretionary. State offenses are entirely outside the power, and governors hold the equivalent authority under state constitutions with widely varying procedures, some requiring board approval. Civil liability, professional discipline, and immigration consequences are not erased, and a pardon does not expunge the record, which remains with a notation. It cannot apply to future conduct, so a pardon for crimes not yet committed is generally understood to be void. Whether a president can pardon himself has never been tested and is disputed.

Practice differs from theory. The Justice Department's Office of the Pardon Attorney runs a review process with waiting periods and standards, but presidents may bypass it entirely and increasingly have. Acceptance of a pardon was characterized by the Supreme Court in 1915 as carrying an imputation of guilt, though later rulings and practice have softened that view, and a pardoned person can generally be compelled to testify since the Fifth Amendment privilege no longer applies to the pardoned conduct. Pardons issued in a president's final days have been a recurring source of controversy across administrations of both parties.