Every US president has the constitutional right to pardon any American citizen for any reason he sees fit.
It is a mysterious and controversial business with notorious past pardons including the likes of Jimmy Hoffa, Caspar Weinberger, Patty Hearst, fugitive billionaire Marc Rich and probably the most provocative, President Gerald Ford's pardon of President Richard Nixon.
The process dates back to the Founding Fathers of America, in particular Alexander Hamilton who made sure that the right to pardon was enshrined in the constitution.
Most pardons are issued to ordinary people who have served their term, become exemplary members of society and want their civil rights restored so they can vote and serve on a jury.
The pardon process
The president can decide to pardon anyone without giving a reason.
If a full pardon is granted, then the crime effectively never happened.
They can also issue a commutation which means that the prisoner can get out of jail early but a record of their crime still remains.
George W. Bush has granted fewer pardons than most presidents, with only 190 to date and nine commutations, against a total of 10,000 requests.
He has most recently let off tax evaders and minor drug dealers.
Anyone wanting a pardon can download a form from the web and email it to the Department of Justice, where three lawyers then assess all the forms and make recommendations to the White House.
The tricky part of the process is being able to get your petition to the top of a very large pile.
With the end of his presidency in sight, Owen-Bennett Jones travels to Washington to see how the system of presidential pardons operates.
He looks at the issue of transparency and questions if power and privilege can buy you a pardon.
Who is President Bush likely to pardon and will any of his decisions become the most controversial yet?
First broadcast Monday 12th January 2008.