Monday's FBI raid on the home of former President Donald Trump — including his safe, according to Trump — has raised eyebrows and questions about what the search could indicate about a possible criminal investigation into the former president and those around him.

The raid concerned presidential records that Trump removed from the White House when he left office in January 2021, according to Christina Bobb, an attorney representing Trump.

The FBI search warrant authorized agents to seize "presidential records or any possibly classified material," Bobb said in a Tuesday interview on the Dinesh D'Souza podcast. The search took about 10 hours, she added.

The execution of the search warrant represents a significant escalation in the investigation that the Department of Justice has been quietly working on for months.

Read on for more about what the raid tells us about the legal questions at stake.

What were the records the FBI was looking for?

We don't know yet what exactly the FBI recovered in the raid. But the search is likely related to the 15 boxes of presidential documents that were removed from Mar-a-Lago earlier this year by the National Archives and Records Administration.

Some of the material recovered then was classified, Attorney General Merrick Garland confirmed in February. The records reportedly included correspondence between Trump and North Korean leader Kim Jong-Un, along with a letter addressed to Trump written by outgoing President Barack Obama.

At the time, the NARA said that representatives for Trump were continuing to "search for additional Presidential records that belong to the National Archives."

It's possible that Monday's raid was conducted to recover those remaining documents.

"The Justice Department is saying, as I read this, 'We're fed up. We don't trust you to be responsive. You're playing games with us, and we're going in and we're taking what you haven't returned, that you promised to return,' " said Stephen Gillers, a law professor at New York University.

What would the FBI have needed to get a warrant?

In short, a search warrant indicates that federal authorities have evidence of ongoing criminal activity at the location where they intend to carry out the search. Warrants are often used in situations where authorities believe a subpoena won't be effective. It is not itself a criminal charge.

Generally speaking, federal agents seeking a warrant must provide an affidavit that contains details about exactly what material they expect to seize during the search and why they believe it is at the location subject to the warrant. A judge reviews the affidavit and signs off on the warrant if they believe the details provided by the agents pass legal muster for probable cause.

"We know that this is not just a bunch of FBI agents who woke up one day and decided to go on a frolic," said Steve Vladeck, a law professor at the University of Texas.

"The more specific the affidavit that accompanies the warrant application is, the better," Vladeck said. "I would suspect that for this particular search of former President Trump's home, the affidavit was probably pretty darn specific."

Importantly, the warrant itself often contains much less information than the affidavit needed to obtain it. The affidavit is typically not made public. A warrant may not say what the suspected crime is, or which person is suspected of committing it.

Who would have had to sign off on this search?

On paper, the standards of federal search warrants are the same for former presidents as they are for ordinary citizens.

But practically speaking, such a politically sensitive search would have to have been approved at the very highest levels of the federal justice system, experts agreed.

Besides the federal judge who approved the warrant, the raid likely needed sign-off by the director of the FBI himself — Christopher Wray, who was appointed in 2017 by President Trump. Additionally, because of the sensitivity, it's likely that Attorney General Garland was involved. A spokesperson for Garland and Deputy Attorney General Lisa Monaco declined comment.

"Garland is a very cautious man. And we can be sure that he wanted to be sure that everything was done beyond criticism," Gillers said.

The White House says it was not involved in the raid. "The president and the White House learned about this FBI search from public reports. We learned just like the American public did yesterday. We did not have advance notice of this activity," said spokesperson Karine Jean-Pierre at a briefing Tuesday.

What possible crimes could be under investigation?

The DOJ has not commented about the raid or investigation. Experts pointed to at least two possible issues that could be under criminal investigation.

One would be the federal statutes that concern the handling of classified material, like some of the records recovered from Mar-a-Lago earlier this year.

"It's a very serious issue when information like this is mishandled," former federal prosecutor Brandon Van Grack told NPR in February, pointing to a federal law that prohibits the unauthorized removal and retention of classified documents. "On its face, if these were top-secret documents and they were not declassified, then they were mishandled."

The second issue is the Presidential Records Act, a 1978 law that requires presidents to preserve all historically relevant material from their time in office — everything from phone logs and national security briefs to emails and handwritten notes — and then hand them over to the National Archives and Record Administration once they leave office.

"Most presidents understand the value of crafting and preserving their legacy, so they show more care (even if it is with a keen editorial eye) preserving their records appropriately," Lauren Harper, director of public policy and open government affairs at the National Security Archive, a nonprofit that advocates for public access to government information, said in an email.

"There has quite simply never been another president so unconcerned with how to handle their records, making the removal and subsequent search unnecessary before now," she said.

Are there any special legal protections for former presidents?

In short, no. While there are significant legal questions about whether a sitting president can be charged with a crime, the same cannot be said of former presidents.

"He really is like a regular citizen, except for the massive political implications and those cannot be understated here," said Kimberly Wehle, a former federal prosecutor who now teaches law at the University of Baltimore School of Law.

And Trump is not simply a former president — he is considering another run for the office in 2024, making him a possible election opponent for Biden, should he run again. The optics of a sitting president's administration charging an opponent cannot be ignored, experts said.

During the 2020 campaign, Biden himself acknowledged the political consequences of such an indictment. "I think it is a very, very unusual thing and probably not very — how can I say it? — good for democracy to be talking about prosecuting former presidents," he said in August 2020.

The White House repeated Tuesday that it is not involved with criminal investigations carried out by the DOJ. "The Justice Department conducts investigations independently, and we leave any law enforcement matters to them," Jean-Pierre said.

Is this unprecedented?

Essentially, yes. The residence of a former president has never been subject to a federal search warrant.

The raid is "a very big deal historically," Wehle said. On the other hand, she said, "there was no precedent for ferrying documents out of the White House this way."

(A president has previously faced criminal investigation. After President Richard Nixon resigned amid the Watergate scandal, he faced the possibility of a federal indictment and trial. Instead, President Gerald Ford pardoned him, effectively ending the investigation.)

What could this mean for Trump's prospects of running for president again?

It's hard to say.

Legally speaking, the Constitution does not prevent a run by a candidate who has been indicted or convicted of most crimes. That could include mishandling classified information or violating the Presidential Records Act.

One possible penalty for "willfully and unlawfully" mishandling public records can be found in Section 2071 of the U.S. criminal code, which calls for anyone found to have done so to be "disqualified from holding any office under the United States."

But there are questions about whether that clause could pass legal muster when it comes to running for president. The Constitution is specific about qualifications to be president and offers impeachment as a remedy to bar people from serving as president. Some legal experts have argued that Congress does not have authority to change those qualifications. The question has not been tested in court.

(The Constitution does bar people who "engaged in insurrection or rebellion" from seeking federal office, but there is not currently any indication that's what's at stake with Monday's FBI search.)

Politically speaking, the raid comes as the Jan. 6 hearings have already caused some damage to the former president's reputation. Some Republicans have expressed unease about a possible Trump 2024 run, and polls show that many Republican voters were already open to an alternative candidate.

On the other hand, Trump is still the biggest name in Republican politics. His endorsement was sought by primary candidates across the country, and in some places it appears to have made a difference.

After Monday's raid, many Republicans are rallying around Trump. Several have demanded that Wray and Garland face questioning by Congress. And House Minority Leader Kevin McCarthy pledged to investigate the DOJ's actions should Republicans retake the House in November.

NPR's Bill Chappell and NPR's Jason Breslow contributed additional reporting.

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