US President Donald Trump on Wednesday pardoned his former national security adviser Michael Flynn, kicking off what is expected to be a string of pardons during the final weeks of the Trump administration.
Mr Trump has granted clemency to supporters before, most notably earlier this year when he commuted the criminal sentence of Roger Stone, who was sentenced to prison after being convicted of lying under oath to lawmakers.
In 2018, Mr Trump even said he had the “absolute right” to pardon himself — a claim many constitutional law scholars dispute.
Here is an overview of Mr Trump's pardon power, which is sweeping but not absolute.
Are there limits on Trump's pardon power?
The pardon power, which comes from the US Constitution, is one of the broadest available to a president. The nation's founders saw the pardon power as a way to show mercy and serve the public good.
While pardons are typically given to people who have been prosecuted, pardons can cover conduct that has not yet resulted in legal proceedings.
A pardon is not reviewable by other branches of government and the president does not have to give a reason for issuing one.
A pardon wipes out a criminal conviction. A different form of executive clemency, known as a commutation, leaves the conviction intact but wipes out the punishment.
But the pardon power is not absolute. Crucially, a pardon only applies to federal crimes. That means pardons would not, for example, protect Trump associates from the criminal investigation being conducted by Manhattan District Attorney Cyrus Vance, a state prosecutor.
Vance’s probe, which began more than two years ago, stemmed from hush money payments that the president’s former lawyer and fixer Michael Cohen paid before the 2016 election to two women — an adult-film star and a former Playboy model — who said they had sexual encounters with Mr Trump. He has denied the encounters and has said the probe is politically motivated.
The district attorney has suggested in court filings that the probe is now broader and could focus on potential bank, tax and insurance fraud, as well as falsification of business records. It is unclear what stage the investigation is at. No one has been charged with criminal wrongdoing.
Could Trump pardon his family members?
Yes. It is legal for Trump to pardon his inner circle, including members of his family.
In 2001, former President Bill Clinton pardoned his own brother, Roger, who was convicted for cocaine possession in Arkansas.
Mr Clinton pardoned about 450 people, including a Democratic Party donor, Marc Rich, who fled the country because of tax evasion charges.
Can Trump pardon himself?
There is not a definitive answer to this question. No president has tried it before, so the courts have not weighed in.
“When people ask me if a president can pardon himself, my answer is always, 'Well, he can try,'” said Brian Kalt, a constitutional law professor at Michigan State University. “The Constitution does not provide a clear answer on this.”
Many legal experts have said that a self-pardon would be unconstitutional because it violates the basic principle that nobody should be the judge in his or her own case. Mr Kalt said that, in his view, was the stronger argument.
Mr Trump could try to pardon himself preemptively to cover the possibility of prosecution after he leaves office.
In that case, the pardon's legitimacy might never be tested in court, said Mr Kalt. For a court to rule on the pardon's validity, a federal prosecutor would have to charge Mr Trump with a crime and then he would have to raise the pardon as a defense, he said.
Could the vice-president take over to pardon Trump?
In a 1974 memorandum, a Justice Department lawyer said President Richard Nixon could not pardon himself but that another option was constitutional: that he temporarily step down, receive a pardon from his vice-president and then regain power.
In order to do that, Mr Nixon would have had to invoke the 25th Amendment of the US Constitution, which allows an incapacitated president to temporarily step down.
Mr Nixon ultimately resigned in the face of the Watergate scandal and almost certain impeachment and removal from office. His successor, Gerald Ford, later pardoned Mr Nixon for any federal crimes he committed or might have committed while in office.
It is not clear what Vice President Mike Pence would have to gain from agreeing to pardon Mr Trump, said Corey Brettschneider, a professor of political science at Brown University.
“I don't think Pence would want that to define his legacy,” Brettschneider said.
