The FBI's seizure of classified documents during its recent search of former President Donald Trump's Florida residence has renewed a debate over whether a former president can assert executive privilege, or the right to shield documents from disclosure. Under the Presidential Records Act, presidential records belong to the government and must be handed over to the National Archives and Records Administration at the end of a president's time in office. The FBI is investigating how hundreds of pages of documents, some classified as top secret, ended up at Mar-a-Lago after Trump left the White House in January 2021. Claiming the documents are "presumptively privileged," Trump has asked a federal judge to stop the FBI from reviewing the records while an independent, third-party assessment is conducted. Trump's claim is not groundless. In 1977, the Supreme Court recognized the right of a former president to assert privilege over certain private communications, and a year later, the Presidential Records Act affirmed that right. But Trump's assertion of executive privilege in this case is highly unusual. Never before has a former president sought to prevent a current president from obtaining his presidential records from the National Archives, according to legal experts. “To the best of my knowledge, it has never been done," said Gary Schmitt, a senior fellow at the American Enterprise Institute, a conservative think tank. Here is a look at executive privilege and the debate over Trump's claim: What is executive privilege? It is a president's right to keep sensitive communications and other presidential records confidential. The idea is that presidents need frank advice to discharge the duties of the office and that candor by advisers requires a promise of confidentiality. Although the practice is not explicitly mentioned in the Constitution, the Supreme Court has recognized the presidential prerogative to keep certain records confidential. The executive branch has interpreted the privilege to cover three categories of documents and communications: state secrets, presidential communications and "deliberative" communications within agencies, according to a recent Congressional Research Service report. The principle is not novel. Presidents going back to George Washington have claimed the privilege, in one form or another, to withhold information. It wasn't until the 1970s, though, that the Supreme Court weighed in on the issue. In 1974, then-President Richard Nixon, asserting that executive privilege allowed him to withhold sensitive information, refused to release White House audio recordings sought by a special counsel and seven defendants in the Watergate case. While recognizing the "privilege of the confidentiality of presidential communications," the Supreme Court ordered Nixon to turn over the tapes. The presidential privilege, the court said, was not "absolute." Does a former president have the right to assert executive privilege? The question is the subject of some debate among scholars. Citing a landmark 1977 Supreme Court case regarding the constitutionality of a law ordering Nixon to transfer the White House tapes and other records to a government agency, some legal experts argue that a former president has an implied authority to assert executive privilege. In the case known as Nixon v. Administrator of General Services, the Supreme Court rejected the government's argument that "only an incumbent president may assert such claims," and it held that Nixon, "as a former president, may also be heard to assert them." The rationale for conferring the privilege on a former president is the same as the sitting president: If aides believed that a president's executive privilege ends with his presidency, so goes the argument, they'd be loath to dispense frank advice. But other scholars note the Supreme Court ruling came before Congress enacted the Presidential Records Act of 1978, giving the incumbent president the ultimate authority to exert privilege. While the Presidential Records Act affirms a former president's executive privilege, in cases of a dispute between a former and incumbent president, it is the current occupant of the White House's authority that matters, according to Schmitt. "A former president certainly can try to make a claim of executive privilege, but it's still the case that the sitting president has the constitutional authorities and also the constitutional responsibilities to judge whether that claim is appropriate or not," Schmitt said. What about Trump's assertion of executive privilege over documents found at Mar-a-Lago? In the year and a half since he left the White House, Trump has asserted executive privilege on several occasions. The first was when the U.S. House committee investigating the January 6, 2021, attack on the U.S. Capitol last year requested Trump White House records from the National Archives. The second came earlier this year when the National Archives informed Trump’s lawyers that the agency wanted to turn over certain classified documents to the FBI. More recently, the former president made the claim after the FBI removed boxes of documents from his residence during the August 8 search. Trump's first two attempts were unsuccessful. In the case involving the congressional committee's request for records, the Biden administration objected to Trump's assertion of "communications privilege," and a federal court agreed. The Supreme Court ultimately upheld the lower court's ruling, though not because of Trump's "status as a former president." In the second case, Trump's lawyers asked the National Archives for additional time to review the records before they were turned over to the FBI. The lawyers wanted to "ascertain whether any specific document is subject to privilege" and give Trump an opportunity to "assert a claim of constitutionally based privilege." The archivist rejected Trump's request, citing a Justice Department opinion that "there is no precedent for an assertion of executive privilege by a former president against an incumbent president to prevent the latter from obtaining" government records from the National Archives. Trump's claim of executive privilege over the documents taken from Mar-a-Lago remains unresolved. If a federal judge accepts Trump's request for a "special master" to review the documents, the former president may decide to assert executive privilege over some records. Dismissing Trump's request as unnecessary, the Justice Department wrote in a filing late Tuesday that any assertion of executive privilege by the former president "would fail here because this case involves the recovery and review of executive records by executive officials performing core executive functions." What makes Trump's claim of executive privilege unusual is that he's asserting it against a current president, said Michael Stern, a former congressional lawyer who writes about legal issues affecting Congress. "In the past, what has come up is issues where outside parties like the Congress or the public is seeking to get information and the former president may, in that situation, assert executive privilege," Stern said. "There's been very little thought, up until now, about the idea that the current president would need to get access to the presidential records of a predecessor, and that predecessor would try to stop him," Stern said. "That is something that I think is the most extreme view of a former president's authority, and one that I think will have a very short life."