Q&A: Libby Spared Prison

What did Mr Bush do?

The president commuted Mr Libby's two and a half year sentence for obstruction of justice and perjury, describing it as excessive. However, Mr Libby - the former chief of staff to the vice-president, Dick Cheney - still faces a $250,000 (£125,000) fine and will remain on probation.

His ability to practice law could be affected by the fact that he was not given a pardon outright. Nevertheless, the president's decision means he will not have to go to jail. It was the first time Mr Bush had used his constitutional power to grant clemency in a controversial case - until now, he had limited his use of the power to routine ones.

How unusual was Mr Bush's decision?

According to the US justice department, requests for commutation are generally not accepted unless and until a person has begun serving their sentence.

Moreover, the decision to commute Mr Libby's sentence goes against Mr Bush's record on clemency when he was the governor of Texas, where he issued fewer pardons than any of the state's governors since the 40s. He gave out only 16 pardons, compared to 70 under his predecessor, the Democrat Ann Richards.

Does the president have total power to commute and pardon?

Yes. Despite the checks and balances in the US political system, the power to pardon and commute sentences lies solely with the president.

The framers of the constitution agreed that the prerogative of mercy was most efficiently and fairly exercised by a single individual rather than a body of legislators or judges. "Humanity and good policy conspire to dictate that the benign prerogative of pardoning should be as little as possible fettered or embarrassed," Alexander Hamilton, one of the foremost interpreters of the US constitution, wrote.

Did Mr Bush consult anyone on the Libby decision?

The president reportedly limited discussions to a few close aides, choosing to consult neither the justice department nor those lobbying on Mr Libby's behalf. He did not consult Patrick Fitzgerald, the chief prosecutor in the case, either, as routinely happens in cases that go through the justice department's pardon attorney.

Administration officials said Mr Bush took his decision after hearing that the US court of appeals had refused to keep Mr Libby out of prison pending his appeal.

Why was Mr Libby sentenced to jail?

He was found guilty of perjury and obstructing the course of justice in an investigation into the "outing" of Valerie Plame as CIA operative in apparent revenge against her husband, a former diplomat who had criticized the case for going to war in Iraq.

What has been the reaction?

Conservatives, on the whole, are delighted - although some think Mr Bush should have gone all the way and granted Mr Libby a pardon.

Democrats are incensed. Harry Reid, the Democratic leader of the senate, called Mr Bush's decision "disgraceful". For his part, Mr Fitzgerald said: "In this case, an experienced federal judge considered extensive argument from the parties and then imposed a sentence consistent with the applicable laws. It is fundamental to the rule of law that all citizens stand before the bar of justice as equals."

Will this damage Mr Bush politically?

He ranks low in the polls in any case, with the worst poll ratings of any modern president, and so probably thought there was nothing to lose.

However, controversial pardons tarnish reputations. Gerald Ford blotted his copybook when he pardoned Richard Nixon, and Bill Clinton sparked an almighty fuss when he pardoned Marc Rich, who fled the US after being prosecuted for tax evasion and was accused of making illegal oil deals with Iran during the hostage crisis.

Mr Bush's father also courted controversy when he pardoned six officials convicted in the Iran-contra affair.