ArtII.S2.C126.96.36.199 Scope of the Pardon Power
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. It has been held, moreover, in face of earlier English practice, that indefinite suspension of sentence by a court of the United States is an invasion of the presidential prerogative, amounting as it does to a condonation of the offense. It was early assumed that the power included the power to pardon specified classes or communities wholesale, in short, the power to amnesty, which is usually exercised by proclamation. General amnesties were issued by Washington in 1795, by Adams in 1800, by Madison in 1815, by Lincoln in 1863, by Johnson in 1865, 1867, and 1868, and by Theodore Roosevelt—to Aguinaldo’s followers—in 1902. Not until after the Civil War, however, was the point adjudicated, when it was decided in favor of presidential prerogative.
The President cannot pardon by anticipation, or he would be invested with the power to dispense with the laws, King James II's claim to which was the principal cause of his forced abdication.
The President may pardon criminal but not civil contempts of court.
A pardon does not return fines paid nor compensation for property taken.
Could a President issue say a pardon for every living person on Earth for all crimes from the beginning of time. Have every murderer, rapist or jaywalker be instantly absolved of his punishment? Would there be anything preventing the President from doing this?
A presidential pardon does not reach any offense that occurred before such law was established by the government of the United States. It does not reach offenses charged by governments, other than the government of the United States.