A pardon is a complete forgiveness of a crime and restores full rights of citizenship. People who have been convicted of a crime forfeit certain rights, such as to hold public office or vote. Because a pardon wipes out the conviction, those rights are restored.
Article II, Section 2, Clause 1 of the Constitution states the president of the United States “shall have Power to grant Reprieves and Pardons for Offences against the United States, except in Cases of Impeachment.”
“The pardon power embraces all ‘offences against the United States,’ except cases of impeachment, and includes the power to remit fines, penalties, and forfeitures, except as to money covered into the Treasury or paid an informer, the power to pardon absolutely or conditionally, and the power to commute sentences, which, as seen above, is effective without the convict’s consent, according to Constitution.congress.gov.
The Justice Department puts is succinctly: “Under the Constitution, only federal criminal convictions, such as those adjudicated in the United States District Courts, may be pardoned by the President. In addition, the President’s pardon power extends to convictions adjudicated in the Superior Court of the District of Columbia and military court-martial proceedings. However, the President cannot pardon a state criminal offense.”
A commutation is a reduction of a sentence to a lesser period of time. The president can commute a sentence if he believes the punishment is too severe for the crime.
While a pardon deletes a conviction, a commutation keeps the conviction but deletes or lowers the punishment. The conviction stays on the record, and the person who receives the commutation does have any rights restored.
A reprieve is a delay or temporary suspension of punishment. Typically, reprieves are granted for very specific and unusual circumstances, such as illness or family emergency. According to clemency.com, a reprieve cannot go on indefinitely so the convicted person doesn’t have to serve their sentence.
Clemency covers all of the above.
According to clemency.com: “As per Clemency law, ‘to grant clemency’ is to give mercy, to forgive. According to the clemency law definition when we speak of an executive’s official power to grant clemency, be it a president or governor, the core of clemency power is to allow the executive personnel to show leniency or mercy. Indeed, it is said to be an act of grace that is based on fairness, justice, and forgiveness.”