Who pardons criminals?

In the United States, it is the executive branch of government that can pardon a convicted criminal. By issuing a pardon, the executive is overruling the decision of the judicial branch (the court system).

Federal crimes can be pardoned by the President. Crimes tried and sentenced in state courts can be pardoned by the governor of that state. The only time a federal or state executive cannot grant a pardon is in cases of impeachment.