The Cohen raid is a game changer: Trump's reaction tells us so

In a diatribe of extravagant narcissism the president called the FBI’s raiding of his lawyer’s premises ‘an attack on our country’

“It’s a disgrace, it’s frankly a real disgrace. It’s an attack on our country in a true sense. It’s an attack on what we all stand for.”

So began Donald Trump’s passionate remarks to reporters before an afternoon meeting of the nation’s top military brass and national security officials. On the agenda was how America should respond to the Syrian government’s most recent chemical weapon attack against its own citizens.

But that criminal attack was not the target of the president’s moral outrage. No, instead it was the news that the FBI “broke into” the office of Michael Cohen, Trump’s longstanding personal lawyer.

“Broke into”, of course, is hardly accurate. Were the president more familiar with the rudiments of the rule of law, he would know that here in the United States the FBI cannot just barge into an office and grab everything in sight. Two down from the president’s beloved second amendment in the constitution is the fourth, which safeguards persons against unreasonable searches and seizures, and requires that search warrants be issued only “upon probable cause”. There must, in short, be a reasonable basis for belief that the search will uncover evidence of a crime. In this case, the heads – as of today – of Trump’s justice department signed off on the FBI’s plans and a federal judge agreed that probable cause had been satisfied.

At this point it’s hard to say what exactly the FBI was searching for. Clearly, though, Mueller’s team is interested in something more than the $130,000 that Cohen paid to Stephanie Clifford, AKA Stormy Daniels – a payment the president claims never to have known about, in order to keep the lid on an affair that he claims never happened. What that something is presumably will only become clear when Trump faces his day of reckoning with Mueller.

For the present, we know the FBI seized tax documents and business records, as well as emails of communications between Cohen and Trump. Such communications are protected by the attorney-client privilege, but that privilege is not absolute. The so-called “crime fraud” exception permits puncturing that privilege if it can be established that the client communicated with the intention of covering up a crime or fraud. The very fact that the FBI sought a warrant and conducted a raid – rather than issuing Cohen with a subpoena – clearly shows that it was worried that the lawyer, who has represented Trump for years and is proud to be known as his “bulldog”, would withhold or destroy evidence of criminal activity.

But the most telling confirmation of the importance of the raid came from the president himself, whose unbalanced diatribe was remarkable even by his standards. We’ve heard the witch-hunt business before: the lasses in Salem had it easy compared to the trials our poor president has had to endure. But in calling a legally authorized raid on the office of his personal lawyer an “attack on our country”, Trump has done more than given strident confirmation to his extravagant narcissism. He has accused the nation’s top intelligence officials and administrators of justice of treason.

We knew this day was coming. Whatever else we might say about Richard Nixon, he went quietly into the night. Not Trump. He will drag us through the misery of a constitutional crisis before, to quote John Brennan, he enters the dustbin of history.

• Lawrence Douglas is the James J Grosfeld professor of law, jurisprudence and social thought at Amherst College, Massachusetts