"We are in a full-fledged constitutional crisis," Sen. Brian Schatz (D-Hawaii) declared on Twitter last night after hearing that Donald Trump had fired FBI Director James Comey. New York Times columnist David Leonhardt agreed. So did Rep. Keith Ellison (D-Minn.) and Sen. Richard Blumenthal (D-Conn.), although Blumenthal described the crisis as "looming" rather than "full-fledged."

Since Trump has the legal authority to dismiss the head of the FBI for a good reason, a bad reason, a transparently insincere reason, or no reason at all, talk of a constitutional crisis is more than a little premature. "Under the Constitution," notes South Texas College of Law professor Josh Blackman, "the president has the absolute power to fire principal officers, such as Director Comey, at will. In that sense, Trump's actions were entirely constitutional."

When it comes to replacing Comey, of course, the Senate will have its say. If senators do their job, they will make sure that Trump does not appoint a toady who will quietly kill the FBI's investigation of possible ties between the Trump presidential campaign and the Russian government. Were Trump to insist that his nominee take over the FBI without Senate approval, that would look more like a constitutional crisis. But so far the process is working as the Constitution prescribes.

If the FBI investigation results in charges against any of Trump's associates, he could use his pardon power to prevent a criminal case from proceeding, which would be unseemly but still constitutional. Trump could respond to any such embarrassment by firing the next FBI director, the attorney general, or both, which would again be within his legal power but politically reckless. If his behavior became appalling enough, Congress would have the power to impeach him. That still would not be a constitutional crisis, since the Framers envisioned and provided for that possibility.

Democrats should take a deep breath. They will need their hot air.