After months of trial balloons from President Trump about the prospect of firing the Federal Reserve chair Jerome Powell, he announced on Monday that he was indeed ousting a Fed official — only it was not Mr. Powell, but Lisa Cook, a member of the Fed’s board of governors.

If Ms. Cook challenges Mr. Trump’s effort to remove her, the courts will have to answer a question of global consequence: Can the president do that?

Under a proper understanding of the Federal Reserve’s place in our constitutional order, the answer should be no. There’s a reason no president has ever tried to fire a Fed governor: It has long been understood that presidents do not get to control the monetary policy decisions of the Federal Reserve, and they can’t get around that prohibition by seeking by fiat to remove the individuals who make decisions about monetary policy.

To dig in deeper on how to understand Mr. Trump’s move, I talked to Lev Menand, a law professor at Columbia, who’s been thinking and writing about the Fed for years.