Yes, The President Can Constitutionally Fire Comey
According to breaking news reports, President Trump has fired FBI director James Comey. The first thing I thought was: can he do that? And the answer is yes, he can.
This 2011 opinion from the Office of Legal Counsel (OLC) provides the relevant law regarding the status of the FBI Director in the Administration. The opinion says that the Office's longstanding position has been that "the FBI Director is removable at the will of the President." It continues:
No statute purports to restrict the President’s power to remove the Director. Specification of a [ten-year] term of office does not create such a restriction. [Cite.] Nor is there any ground for inferring a restriction. Indeed, tenure protection for an officer with the FBI Director’s broad investigative, administrative, and policymaking responsibilities would raise a serious constitutional question whether Congress had “impede[d] the President’s ability to perform his constitutional duty” to take care that the laws be faithfully executed. Morrison v. Olson, 487 U.S. 654, 691 (1988).
Firing Comey is likely a bad idea, but we probably don't have a constitutional crisis on our hands. Yet.