There is no universally accepted definition of a constitutional crisis, but legal scholars agree about some of its characteristics. It is generally the product of presidential defiance of laws and judicial rulings. It is not binary: It is a slope, not a switch. It can be cumulative, and once one starts, it can get much worse.

It can also be obvious, said Erwin Chemerinsky, dean of the law school at the University of California, Berkeley.

“We are in the midst of a constitutional crisis right now,” he said on Friday. “There have been so many unconstitutional and illegal actions in the first 18 days of the Trump presidency. We never have seen anything like this.”

His ticked off examples of what he called President Trump’s lawless conduct: revoking birthright citizenship, freezing federal spending, shutting down an agency, removing leaders of other agencies, firing government employees subject to civil service protections and threatening to deport people based on their political views.

That is a partial list, Professor Chemerinsky said, and it grows by the day. “Systematic unconstitutional and illegal acts create a constitutional crisis,” he said.

The distinctive feature of the current situation, several legal scholars said, is its chaotic flood of activity that collectively amounts to a radically new conception of presidential power. But the volume and speed of those actions may overwhelm and thus thwart sober and measured judicial consideration.