The Federal Bureau of Investigation’s raid on President Trump’s Mar-a-Lago residence means that the investigation of the onetime president has reached a perilous new phase.

News of the raid was broken by Mr. Trump himself in a lengthy statement this evening on his Truth Social platform. He wrote that his “beautiful home” was “currently under siege, raided, and occupied by a large group of FBI agents.”

The former president went on to say that “after working and cooperating with the relevant Government agencies” the “unannounced raid on my home was not necessary or appropriate.” He called the raid “prosecutorial misconduct.”

“Nothing like this has ever happened to a President of the United States before,” Mr. Trump keened. CNN reports that the former president was not at Mar-a-Lago during the raid.

The FBI issued no official statement concerning the raid or any explanation of what is being sought. The 4th Amendment of the United States Constitution requires that a warrant must be issued for a search like this and name the persons or things to be seized.

Such warrants, though, are not typically made public, at least not in the early stages of an investigation, and it might be some time before we know exactly for what the authorities were searching or what, if anything, they removed from Mar-a-Lago.

CNN and the Associated Press have reported that the warrant relates to the one-time president’s handling of confidential documents. It came on a day in which Axios had published pictures of what it claimed were notes handwritten by the President torn up and flushed down the toilet.

The contents or nature of those documents have not been identified. Those pictures, allegedly of one toilet at the White House and another from “an overseas trip,” might, moreover, have nothing to do with any object for which the FBI was searching at Mar-a-Lago. The Federal Records Act governs the disposition of many presidential materials.

Warrants of the kind that would have allowed access to Mar-a-Lago are obtained when prosecutors convince a judge that there is probable cause to believe that a specific crime is occurring at the place to be searched or that evidence of a crime may be found on the premises. “Probable cause” is a standard found in the Fourth Amendment of the Constitution. 

That amendment reads in full: “The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”

Mr. Trump has been under federal investigation for mishandling of confidential documents that were taken to Mar-a-Lago after the end of his presidency. In the spring, subpoenas were issued to the National Archives, which retrieved 15 boxes of documents from Mr. Trump’s Florida home. 

The January 6 Committee has also shined a harsh spotlight on the former commander-in-chief, who has already been tried in two impeachment and discovered in each of them to be “not guilty,” to use the language the Senate used in announcing the verdicts at the two trials.

Being no longer president, Mr. Trump is vulnerable to be charged in regular court for any crimes he might have committed before, during, or after his presidency. The Department of Justice has thus far not moved to charge Mr. Trump, although Attorney General Garland in recent days twice, in response to questions, repeated “no person is above the law.”

Any conviction of Mr. Trump would require the finding of guilt beyond a reasonable doubt, and against a much stricter standard of proof than obtains for an impeachment, in which a finding of guilty requires only two-thirds of the “jury,” meaning the Senate. In criminal court, a jury would have to agree on any guilty verdict unanimously.

In heaping scorn on the raid Monday evening, Mr. Trump said, “What is the difference between this and Watergate?” Nor is he the only figure to express outrage at the raid. The House minority leader, Congressman Kevin McCarthy, said in a statement in response to the raid “I’ve seen enough.” He added “The Department of Justice has reached an intolerable state of weaponized politicization.”

“When Republicans take back the House,” Mr. McCarthy added, “we will conduct immediate oversight of this department, follow the facts, and leave no stone unturned.” He called on the attorney general to “preserve your documents and clear your calendar.”