Attorney-client privilege is a pretty nifty thing. A person can confess a past crime to his attorney, and the attorney won’t tell anybody.

The key word is “past,” and it could be an important caveat after the FBI raided the office, home and hotel room of Michael Cohen, President Trump’s longtime lawyer.

Among the evidence seized by federal agents were documents related to a $130,000 payment made shortly before Election Day 2016 to Stormy Daniels, the porn star who says she had an affair with Trump more than a decade ago. Cohen has said he paid Daniels with his own money, and Trump has said he did not know about the payment at the time.

Whether Trump knew about the payment is a key point, because according to former Federal Election Commission chairman Trevor Potter, Cohen’s payment to Daniels could be construed as an illegal in-kind contribution to Trump’s campaign.

“If Trump and Cohen conspired to break the law by having Cohen make a $130,000 in-kind contribution, are their communications covered by the attorney-client privilege? No,” said David Alan Sklansky, a former federal prosecutor who serves as faculty co-director of the Stanford Criminal Justice Center. “If your communications with your lawyer are designed to have the lawyer do something that would be a crime, that’s not covered by the privilege.”

Trump fumed about the FBI raid on Monday night, telling reporters that it was a “disgrace” and an “attack on our country.” He continued to rage on Tuesday, tweeting, “Attorney–client privilege is dead!”

In the Stormy Daniels case, Trump might be right — if by “dead” he means that attorney–client privilege would not shield him. But this “crime-fraud exception,” as it is known, is not new. The American Bar Association explains:

The crime-fraud exception was first recognized in the United States over one hundred years ago, and the policy behind it is well-defined. (The crime-fraud exception was first recognized in the United States in Alexander v. U.S., 201 U.S. 117, 121 (1906).) The legal community does not deem discussions concerning future wrongdoings, such as fraud, that occur during an attorney-client communication worthy of protection. … While the practice of law encourages full and frank communications between the attorney and client, only communications concerning past wrongdoings are protected.

A lawyer for Cohen, Stephen Ryan, has asserted that documents seized by the FBI are covered by attorney-client privilege.

But “the fact that they got a warrant under these circumstances shows that they had to meet a higher bar than you would normally have to meet to obtain a warrant,” said Jessica A. Levinson, a professor at Loyola Law School in Los Angeles.

“There are so many people who are high-ranking officials along the way who had to look at the evidence and say, yes, there’s enough there for a warrant.”

Some of those officials high-ranking officials within the Justice Department were, of course, picked by Trump.