The phrase, "shall have power to grant reprieves and pardons for offences against the united states, except in cases of impeachment" is from the u. s. constitution. it describes the power of the

The power to pardon is one of the least limited of the President in the Constitution.

Pardons are limited to offenses against the United States considering that they don't affect an impeachment process. The logic is the alleviation of the sentence. A pardon does not give the President the power to relinquish the laws. Indeed, it cancels the legal status of convicted. The pardon power has been a powerful tool of the President. Its use might be good for the polity or it might increase political conflict.