Based on what we know, there are three major legal takeaways from the FBI's search of Donald Trump's Florida home on Monday.
First, this is a big deal, historically and constitutionally speaking. As far as I can tell, a criminal search warrant has never been executed against a former president.
Second, from the perspective of criminal investigation, the surprise raid was a highly unusual, aggressive step. In almost all criminal investigations of nonviolent conduct, the Federal Bureau of Investigation and Department of Justice would have requested cooperation from the defendant's lawyers, not surprised the defendant and broken into his safe.
And third, despite the drama, executing the search warrant is far from a guarantee that any criminal action will be taken. In fact, there is some reason to think that the public raid will take some of the heat off Attorney General Merrick Garland, whom President Joe Biden has been urging to act against Trump — without forcing him into a prosecution decision he has strong reason to avoid.
Start with history. Other former presidents have been in trouble. But they managed to avoid criminal prosecution, and that includes, it would appear, being made subject to a search warrant.
Richard Nixon never handed over missing portions of the Watergate tapes. But he was pardoned by President Gerald Ford, rendering that investigation effectively inoperative. Aaron Burr was a former vice president when he was arrested and criminally charged with treason in 1807. That's probably the closest we've come to the current scenario.
The constitutional significance of this step in the criminal investigation of Trump is that a sitting administration must be extremely cautious and thoughtful about prosecuting the predecessor president. True, under the Constitution, no one is above the law, as the Supreme Court has repeatedly emphasized. Yet the fact that the power to prosecute criminally rests with the executive branch, not an independent prosecutor, means it is up to the sitting president to make sure our system doesn't devolve into a series of retaliatory prosecutions of former government officials.
Think of it this way: If it became at all normal for the administration of a new president to prosecute the one who came before him, it would be difficult to avoid a tit-for-tat repetition each time the president came from a different party. You can see this danger in the immediate calls by Republicans to investigate Garland.
Few things could be more disruptive to constitutional democracy than the use of the presidency to seek criminal charges against former presidents. The pragmatic reality underlying a rights-based constitutional system is that the party in power must remember that it, too, will be out of power someday. It therefore must respect the rights of the party that came before, not just out of principle, but out of the practical realization that the whole system will collapse unless both sides follow the rules of respecting each other.
This reality naturally leads to the question of why the FBI and Justice Department took this very aggressive step against Trump. Obviously, if a former president has committed serious crimes, that breaks the norms and provides reason to investigate.
But no rational prosecutor could think it was a good idea to prosecute a former president unless he could easily be convicted of something serious. An acquittal would be bad for the rule of law because it would suggest retrospectively that the prosecution had been illegitimate or political. Even a conviction on a relatively trivial charge would look politically motivated.
Here a puzzle must be acknowledged. Getting a conviction against Trump on a charge of retaining classified documents would seem to be very tricky.
He could claim that, as president, he declassified the documents — an act that would have been within his power to do while in office. Then taking them would not have been a crime. Even if somehow this defense could be overcome, the offense doesn't seem egregious enough to bring charges against a former president who is still eligible to run for the presidency again.
The puzzle, then, is why the search warrant was executed. Either prosecutors are seriously considering a documents-based charge; or they were worried the classified documents were vulnerable to exploitation in Trump's safe; or some other investigation is going on that we don't know about; or some other motivation is in play.
Before executing a search warrant against a former president, FBI and Justice Department officials would have to seek approval at the highest levels. It seems almost inconceivable that Garland would not have been consulted. That means the decision to up the ante so drastically and publicly in the Trump criminal investigation was considered, not to say calculated.
In a normal white-collar criminal case, defense lawyers would be outraged by the execution of the search warrant against their client. By executing it, the prosecutors would be sending a message that they were treating the defendant with a high degree of contemptuous suspicion, and certainly not anticipating collegial plea negotiations. It would ordinarily be read as a sign of great confidence on the part of the prosecutors that they were going to be able to bring charges.
For Garland's Justice Department, however, the public nature of the raid arguably functions a little differently. Garland has had to deal with Biden's public frustration with the pace of the investigation. Now, after this raid, neither the president nor the Democratic base can complain that the investigation is not being taken seriously.
Coupled with this benefit to the Justice Department is that executing the warrant doesn't require any subsequent decision to prosecute — no matter what was found. The attorney general enjoys full prosecutorial discretion.
So don't assume that this raid means the federal government will prosecute Trump. The odds still remain low of any such criminal prosecution.
The risks associated with Trump's reaction are still very great. A prosecution could backfire in numerous ways, including by giving Trump greater incentive to run for office and win in order to fend off the prosecution or its consequences.
Garland knows all this, and remains committed, I believe, to reestablishing the rule of law and the nonpolitical nature of federal criminal investigation and prosecution. He is an extraordinarily difficult position. Searching Trump's Florida house may simply have been part of making sure no stone was left unturned in the investigation, even if no charges are ever brought against Trump.
Noah Feldman is a professor of law at Harvard University and author, most recently, of "The Broken Constitution: Lincoln, Slavery and the Refounding of America."