"Article II, Section 2, of the Constitution says that presidents “shall have Power to grant Reprieves and Pardons for Offenses against the United States, except in Cases of Impeachment.” The Supreme Court has held that this power is unreviewable, writing in United States v. Klein that the president’s pardon power “is granted without limit” and reiterating that “Congress can neither limit the effect of his pardon, nor exclude from its exercise any class of offenders.” Because pardons are a combination of mercy and largesse, they’re often issued with abandon when a president is preparing to leave office."
