The presidential pardon power is the authority granted to the President of the United States to forgive or excuse a person convicted of a crime, either before or after the conviction has taken place. The pardon power is granted by the U.S. Constitution and can be used to commute a sentence, grant clemency, or completely forgive an individual's crime. The pardon power is considered to be one of the most powerful tools of the presidency, as it allows the President to override the decisions of the judicial system.