The F.B.I. Search of Trump’s Home Has No Precedent. It’s a Risky Gamble.

WASHINGTON — The fight between former President Donald J. Trump and the National Archives that burst into the open when F.B.I. agents searched Mr. Trump’s Palm Beach estate has no precedent in American presidential history.

It was also a high-risk gamble by Attorney General Merrick B. Garland that the law enforcement operation at Mar-a-Lago, the former president’s sprawling home in Florida, will stand up to accusations that the Justice Department is pursuing a political vendetta against President Biden’s opponent in 2020 — and a likely rival in 2024.

Mr. Trump’s demonization of the F.B.I. and the Justice Department during his four years in office, designed to undermine the legitimacy of the country’s law enforcement institutions even as they pursued charges against him, has made it even more difficult for Mr. Garland to investigate Mr. Trump without a backlash from the former president’s supporters.

The decision to order Monday’s search put the Justice Department’s credibility on the line months before congressional elections this fall and as the country remains deeply polarized. For Mr. Garland, the pressure to justify the F.B.I.’s actions will be intense. And if the search for classified documents does not end up producing significant evidence of a crime, the event could be relegated by history to serve as another example of a move against Mr. Trump that backfired.

Mr. Trump faces risks of his own in rushing to criticize Mr. Garland and the F.B.I., as he did during the search on Monday, when he called the operation “an assault that could only take place in broken, Third-World Countries.” Mr. Trump no longer has the protections provided by the presidency, and he would be far more vulnerable if he were found to have mishandled highly classified information that threatens the nation’s national security.

A number of historians said that the search, though extraordinary, seemed appropriate for a president who flagrantly flouted the law, refuses to concede defeat and helped orchestrate an effort to overturn the 2020 election.

“In an atmosphere like this, you have to assume that the Attorney General did not do this casually,” said Michael Beschloss, a veteran presidential historian. “And therefore the criminal suspicions — we don’t know yet exactly what they are — they have to be fairly serious.”

In Mr. Trump’s case, archivists at the National Archives discovered earlier this year that the former president had taken classified documents from the White House after his defeat, leading federal authorities to begin an investigation. They eventually sought a search warrant from a judge to determine what remained in the former president’s custody.

Key details remain secret, including what the F.B.I. was looking for and why the authorities felt the need to conduct a surprise search after months of legal wrangling between the government and lawyers for Mr. Trump.

The search happened as angry voices on the far-right fringe of American politics are talking about another Civil War, and as more mainstream Republicans are threatening retribution if they take power in Congress in the fall. Representative Kevin McCarthy of California, the Republican leader in the House, warned Mr. Garland to preserve documents and clear his calendar.

“This puts our political culture on a kind of emergency alert mode,” said Douglas Brinkley, a presidential historian at Rice University. “It’s like turning over the apple cart of American politics.”

Critics of Mr. Trump said it was no surprise that a president who shattered legal and procedural norms while he was in the Oval Office would now find himself at the center of a classified documents dispute.

For nearly 35 years, the tug of war over presidential records — and who controls them — has been a largely bureaucratic one waged in the halls of the National Archives and debated among lawyers in courtrooms.

Former President Richard M. Nixon spent nearly four years after Watergate fighting for control over millions of pages of presidential records and hundreds of hours of the audiotapes that helped force his resignation. Mr. Beschloss said that Nixon initially reached a deal with President Gerald R. Ford that would have given him control over his papers as well as the ability to destroy them. But an act passed by Congress after Nixon left office in August 1974 forced him to take his fight to court. He eventually lost in the Supreme Court, 7-2.

The dispute led to the passage in 1978 of the Presidential Records Act, which for the first time made it clear that White House records are the property of the federal government, not the president who created them. Since then, presidents from both parties have haggled over how and when the archives may release those documents to the public.

Presidents and their aides have also been subjected to other laws concerning the handling of classified information. Over the years, a handful of top federal officials have been charged with illegally handling classified information.

David H. Petraeus, the Army general who served as C.I.A. director under former President Barack Obama, admitted in 2015 that he provided his highly classified journals to his lover, pleading guilty to one count of unauthorized removal and retention of classified material, a misdemeanor.

Sandy Berger, who was national security adviser for former President Bill Clinton, paid a $50,000 fine after pleading guilty to removing classified documents from the National Archives in 2003 to prepare for his testimony to the 9/11 Commission.

But there has never been a clash between a former president and the government like the one that culminated in Monday’s search, said Lee White, the executive director of the National Coalition for History.

Mr. White, who has met frequently over the years with officials at the National Archives, said they usually work hard to resolve disagreements about documents with former presidents and their advisers.

“They tend to be deferential to the White House,” Mr. White said of the lawyers at the National Archives. “You know, these questions come up about presidential records and they are like, ‘Look, our job is to advise the White House.’ But they are not, by nature, an aggressive group of attorneys.”

Mr. Beschloss and Mr. Brinkley both said the search of Mr. Trump’s house has the potential to become a flash point in the ongoing struggle between those investigating the former president’s actions and the forces who supported Mr. Trump’s frantic efforts to stay in office.

But they said there were also risks for Mr. Trump and his allies on Capitol Hill, who on Monday rushed to attack Mr. Garland and the F.B.I. in the hours after the search.

“You now have Kevin McCarthy — something else we’ve never seen before in history — making ugly threats to an attorney general, obviously trying to intimidate him,” Mr. Beschloss said.

Mr. Trump’s defenders did not wait to find out what evidence the F.B.I. found or even sought before using the search to ratchet up longstanding grievances that the former president stoked throughout his time in office. Senator Marco Rubio, Republican of Florida, quickly distributed a short video on Twitter accusing the Biden administration of acting like the regime of a dictator in a third-world country.

“This is what happens in places like Nicaragua,” Mr. Rubio said in the video. “Where last year every single person that ran against Daniel Ortega for president, every single person that put their name on the ballot, was arrested and is still in jail.”

“You can try to diminish it, but that’s exactly what happened tonight,” Mr. Rubio said.

The historians said the events are a test of the resilience of American democracy when it is under assault.

“We are in the middle of a neo-civil war in this country,” Mr. Brinkley said. “This is a starkly unprecedented moment in U.S. history.”