Donald Trump will be the first president to take office while being a convicted felon, with state and federal criminal cases still pending. State-level convictions remain beyond presidential powers, but Trump’s re-election seemingly means the end of those federal cases — and soon.

Former Suffolk County Sheriff Andrea Cabral explained on Boston Public Radio on Thursday that there is a memo within the Department of Justice that says the attorney general cannot indict or prosecute a sitting president.

During the Watergate scandal in 1973, the Office of Legal Counsel issued a memo stating that a sitting president could not be indicted or tried, arguing that it would unconstitutionally undermine the executive branch’s ability to perform its duties.

“It’s just a memo,” Cabral said. “It’s not like a policy set in stone. But they have been following it.”

Cabral argued that the memo’s legal significance is further questioned since it has only been applied once, during the Richard Nixon era.

She noted that Special Counsel Jack Smith is taking steps to “wind down” the federal cases against Trump before he takes office in 2025, but added that nothing in the memo “says they have to start winding it down now.”

Trump said if he were re-elected, he would fire Smith “within two seconds” of taking office.

Cabral suggested the decision to wind down the cases is because there’s no longer a possibility of going to trial. She said it’s also possible officials do not want “to anger [Trump] any further.”

But even if the case were to continue and result in a conviction, legal scholars believe a president has the power to self-pardon. Trump has suggested in interviews that he would not do that.

As to whether President Joe Biden should preemptively pardon Trump, Cabral firmly believes the answer is no.

“I’ve never even heard of a preemptive pardon. Pardons come after convictions,” she said.

She added that a preemptive pardon would send the message that some people are above the law.

“If Joe Biden were to pardon Trump,” Cabral said, “the first thing Trump would say is 'I was pardoned because we never did anything wrong. And that’s why I’m pardoning all of the Jan. 6 people.’”

Trump has made comments on the campaign trail that he would offer clemency to those defendants.