This week, US President Joe Biden made the controversial decision to pre-emptively pardon his son Hunter for any federal crimes "he committed or may have committed" between January 1, 2014, and December 1, 2024.
It's a power almost every president since George Washington has taken advantage of, to varying reception.
Here's what to know about the power and its fraught history.
What is the presidential pardon?
During their time in office, US presidents have what's known as the Presidential Pardon Power.
Outlined in Article II of the Constitution, it allows the president to grant clemency for any federal crime.
Pardoning a convicted criminal immediately restores their civil rights and right to bear arms.
The conviction will not be erased or expunged from their criminal record, though.
There are only a handful of limitations for presidents using the power:
- The power doesn't extend to state-level offences
- Clemency can't be granted to people who have been impeached
Presidents don't need to provide an explanation for their pardons.
Under this power, presidents can also grant commutations — that is, a reduction of someone's sentence, either totally or partially.
How hard is it to get a presidential pardon?
The process can take several years.
For most people convicted of federal crimes, they must submit an application, which is then referred for review
Could Trump pardon himself?
Donald Trump is both the first former president to be convicted of a crime and the first criminal to be elected president.
So, could he use his pardoning powers to grant himself clemency?
It wouldn't be a sure-fire solution to his legal woes for a few reasons.
First, the two federal cases against him have been dropped, thanks to the Department of Justice's policy against prosecuting sitting presidents.
That leaves two criminal cases still in limbo:
- His New York hush money case, in which he has been found guilty
- His Georgia election interference case, which has been on hold for months
A presidential pardon would be useless for both of these cases, as the powers don't extend to state cases.
Even if that rule didn't apply, there's also the matter of whether a president would actually be allowed to pardon themself.
That question arose back in the 1970s when Richard Nixon was president.
At the time, Mary C Lawton, who was then acting as assistant attorney general, wrote:
"Under the fundamental rule that no one may be a judge in his own case, the president cannot pardon himself."
This assertion hasn't been legally tested in court, though.
No president has ever attempted to pardon themself, so we don't know how such a move could be challenged and what verdicts judges might make on the matter.
Can a president pardon a family member?
Yes — and Mr Biden isn't the first to do so.
On December 23, 2020, Donald Trump issued a full and unconditional pardon to Charles Kushner, his daughter Ivanka's father-in-law.
And on his last day in office, Bill Clinton pardoned his half-brother Roger Clinton, who had pleaded guilty to drug charges in 1985, for which he spent a year in prison.
Can a presidential pardon be overturned?
It's not exactly clear.
Congress and courts can't reverse them but there are precedents for a president doing so before delivery and acceptance.
In 2008, for instance, George W Bush revoked a pardon he granted Isaac Robert Toussie — a real estate agent convicted of mail fraud — the day after learning his father was a major donor for the Republican Party.
That was allowed because the pardon attorney had not yet signed the grant of clemency.
Trump likely won't be get the chance to revoke Hunter Biden's pardon under the same circumstances, though — it's still more than a month until he returns to office and by that time, the clemency will have been finalised.
The Supreme Court hasn't issued an opinion outlining exactly when a pardon becomes irrevocable, so it remains to be seen whether an attempt to overturn the pardon could be successful by Trump.
How many pardons has Biden given?
So far, he's pardoned just 26 people.
But with more than a month left of his presidency, that number could be about to jump.
Presidents tend to grant petitions for clemency at a higher rate in the last days of their administrations than earlier in their terms.
Who did Donald Trump pardon in his first term?
In his first term, Mr Trump pardoned or commuted the sentences of 144 people, including Kushner.
Five were former campaign staff members and political advisers:
- Paul Manafort
- Roger Stone
- Michael Flynn
- Stephen Bannon
- George Papadopoulos
Bannon had been charged with conspiracy to commit mail fraud and money laundering in connection to a Trump fundraising campaign, We Build the Wall.
While he was pardoned for those charges, he went on to serve time in federal prison after being convicted for rejecting a subpoena from a congressional panel investigating the January 6, 2021, attack on the US Capitol.
One of Trump's other pardons came after celebrity Kim Kardashian personally lobbied the then-president on Alice Marie Johnson's behalf.
Johnson was found guilty of first-time drug trafficking charges in 1996 and had been serving life in prison.
Trump first commuted her sentence in 2018, but went on to grant her a full pardon in 2020 after she praised his leadership at that year's Republican National Convention.
Why did Ford pardon Nixon?
Perhaps the most infamous case of a presidential pardon was Gerald Ford's choice to grant a pre-emptive one to his predecessor, Richard Nixon.
That related back to the Watergate scandal, where several intertwined political scandals were revealed following the arrest of five burglars at the Democratic National Committee headquarters in the Watergate complex in Washington, DC on June 17, 1972.
While Nixon was never charged with any crimes, he went on to resign from office when it became a near-certainty that he would be impeached over his connection to Watergate.
He was replaced by Mr Ford, who said in a televised broadcast that it was in the nation's best interests that Mr Nixon be granted a pardon for any crimes he may have committed while president.
"It could go on and on and on, or someone must write the end to it," he said.
"I have concluded that only I can do that, and if I can, I must."
