The FBI’s search of and seizure of documents from Donald Trump’s Mar-a-Lago resort in Florida is not only dramatic and serious, but unprecedented: no other former president has faced such an action. Yet Mr Trump’s ability to survive and thrive politically on similar moments is also without precedent. Even when damaging evidence emerges, he has walked away largely unscathed in the eyes of his base, while the US itself has been diminished. Nor has he yet experienced legal consequences for his actions in office.

Monday’s search was reportedly part of the ongoing investigation examining his potentially unlawful removal and destruction of White House documents. Accurately recording the actions of a country’s executive is part of democratic accountability. But this investigation will also help to determine the future: first, and most importantly, because upholding standards maintains the difference between honest and transparent systems and dishonest and unaccountable ones, and second, through its electoral impact.

Mr Trump has long been known for extreme carelessness at best regarding records. Earlier this year, a senior official said that “he never stopped ripping things up”, and a new book will report that White House staff believed he clogged toilets by attempting to flush away wads of paper. In February, 15 boxes of documents and other items were retrieved from Mar-a-Lago by the National Archives. The legal requirements for a search such as Monday’s are substantial, and the likely fallout such that it was almost certainly approved by the attorney general, Merrick Garland, who is known for his caution. It is hard to imagine that mementoes of office were all that was at stake.

Moreover, this is only one of multiple investigations involving Mr Trump, and not the most important. The Department of Justice has expanded its investigation into the storming of the Capitol on 6 January 2021 to cover his statements and behaviour, as well as requesting evidence from the House select committee’s inquiries.

The search comes on top of a welcome streak of good news for Joe Biden, albeit not yet enough to provide the kind of shift in polling that Democrats need before November’s midterms. Yet Mr Trump has prospered by weaponising such moments. (It is typical that he should invoke Watergate, thinking not of presidential wrongdoing, but the illegal break-in at Democratic headquarters.) Just as worryingly, senior Republicans have again rallied to him as a Maga martyr pursued by a “witch-hunt”, with no shame about their desire to “lock her up” when the FBI investigated Hillary Clinton over her use of a private email server as secretary of state. Beyond that, 6 January was horrifying evidence of the peril of deep political divides mutating into outright violence and attacks upon democratic institutions.

It is surely not narcissism alone which impels the former president to signal that he wants to run again. A campaign would not prevent him being prosecuted (and it is far from clear that conviction under the law on removing official records would bar him from office, as some hoped). But it would raise the political stakes, and might lead to him enjoying presidential immunity again. If he believes he is in a race with investigators, he may be prompted to make an early announcement.

Nonetheless, pursuing Mr Trump over serious allegations is essential. To simply ignore potential crimes because the investigations might be exploited politically would amount to granting de facto immunity to those who stir up the most turmoil. Worse, if action is not taken now, it could become impossible in a second Trump term, under a president and aides who have already shown their eagerness to eradicate the country’s checks and balances, and who will have learned better how to do so.