The president is an elected official, and Americans live in a free society. So, when he grants an unpopular pardon, the public feels free to complain. President Bush was reminded of this after Libby's commutation, and countless other presidents have received feedback on their decisions as well.
President Gerald Ford is widely considered to have lost the 1976 election by pardoning his predecessor, President Richard M. Nixon; President Bill Clinton was nearly indicted for one of the 459 pardons he issued during his two terms in office. But ultimately, when granted appropriately, there's no way to block or even review a presidential pardon.
When dealing with a political tool as powerful as this, debate over its use is guaranteed to arise in the other branches of government. Congress often bites its collective tongue in frustration during pardon season, which tends to come hardest and fastest late in a president's final term. Yet, deep down every Congressman knows that the pardon is untouchable: It would take a constitutional amendment to make any change to the pardon power.
Article II, Section 2 of the Constitution gives the executive officer of the United States the power to pardon. The wording is at once succinct and sweeping: " … [the president] shall have Power to Grant Reprieves and Pardons for Offenses against the United States, except in Cases of Impeachment [Source: USConstitution.net]."
In the next section, we'll look at a few cases of presidential pardons, including Patty Hearst and Tokyo Rose.