Once confined to scholarly circles, the debate over whether a president can pardon himself has gained urgency in the wake of last week's violent storming of the U.S. Capitol by President Donald Trump's supporters.
The riots led to Trump's historic second impeachment this week and sparked Democratic calls for a federal investigation into Trump's role in inciting the violence.
That in turn has renewed the question of whether Trump may use the power of presidential pardon on himself in order to escape future prosecution.
It is something that Trump has broached in the past. In 2018, facing a special counsel investigation into his 2016 campaign's ties to Russia, Trump said he had an "absolute right" to pardon himself.
But as far-fetched as it may sound, a self-pardon may not necessarily be in Trump's best interest, and advisers have reportedly tried to talk him out of it. Self-clemency can be viewed as an admission of guilt, they've said. What is more, it may backfire by prompting an otherwise reluctant Department of Justice under incoming President Joe Biden to challenge the pardon and bring charges against Trump, according to legal experts.
Here is a primer on the debate over whether Trump can pardon himself before he leaves office.
Can the president pardon himself?
The U.S. Constitution itself is mum on the matter. Article II of the charter gives the president the power to "grant reprieves and pardons for offenses against the United States, except in cases of impeachment." That broadly-worded text has left it open to interpretation.
"No president has ever tried a self-pardon, so we don't have any precedent," said Jeffrey Crouch, a law professor at the American University and author of a book on presidential pardon power. "President Nixon thought about doing it but ultimately opted not to."
Those who believe a president can self-pardon argue that there is nothing to the contrary in the Constitution. The American leader, they say, has the power to pardon federal crimes, and if he himself commits a federal crime, then he should be able to pardon himself for that offense.
But those who take the opposite view – and they're in the majority – contend that the very act of "granting a pardon" implies a bilateral move involving two people.
"The use of the word pardon normally connotes one person is pardoning another. That is the way it's been understood historically," said Steve Mulroy, a law professor at the University of Memphis.
What is more, Mulroy said, self-pardoning is at odds with a long-standing American legal principle, rooted in English law, that one cannot be a judge in one's own case.
"So for that reason, while the pardon power is very broad and the Supreme Court has never definitively ruled, most constitutional scholars would say that you can't pardon yourself," Mulroy said.
In 1974, the Justice Department considered the question. The answer it came up with was no. Self-pardoning would run counter to the "the fundamental rule that no one may be a judge in his own case," the department's Office of Legal Counsel wrote in a memo.
The memo remains Justice Department policy.
What would a self-pardon look like?
Of course, that doesn't mean the president may not try to pardon himself. If he opted for self-clemency, he'd likely issue himself a "full and unconditional pardon," according to legal experts. Typically, when a president pardons someone, the clemency document specifies the charges he's pardoning them for, as was the case with Trump's recent pardons of several former associates.
In his own case, though, Trump would likely opt for a blanket pardon, modeled on the pardon of former President Richard Nixon, for all crimes against the United States, said Caroline Mala Corbin, a professor of law at the University of Miami.
What are the implications of a presidential self-pardon?
Never tried before, a self-pardon by Trump could set a potentially dangerous precedent for future presidential conduct, according to some legal experts.
"Presidential self-pardons would be a terrible precedent and allow presidents to commit the most atrocious federal crimes and simply pardon themselves," Corbin said.
Those who think a president can pardon himself disagree, however, saying that there are other checks on presidential power such as impeachment by Congress. Plus, a pardon doesn't protect a president from state prosecution.
Can a self-pardon be legally challenged?
While presidential pardons are permanent and can't be undone, a self-pardon by Trump could end up facing legal challenges in the future.
Biden has made clear he does not favor having the Justice Department investigate his predecessor. But if Trump were to pardon himself, that could prompt the Justice Department to bring charges against him if only to test the constitutionality of self-clemency.
The issue could go all the way before the Supreme Court, which has never weighed in on the question, experts say.
"It could easily be argued that this was an issue of constitutional law that had to be settled by the courts and not politically motivated," Corbin said.
The threat of DOJ action in response to a self-pardon could in turn dissuade Trump from considering pardoning himself in the first place, she added.
Can Trump resign and have Vice President Mike Pence pardon him?
This remains a possibility even though Trump has made no indication that he plans to resign before his term ends on January 20. There is a precedent for a president receiving a pardon from his successor.
In 1974, after Nixon resigned over the Watergate scandal, his vice president and successor, Gerald Ford, issued him a blanket pardon for all crimes against the United States. While Ford insisted he did it in the national interest, to critics, the clemency always looked like a "self-pardon" by Nixon.