The White House announced last week that President Trump was considering revoking the security clearances of six former intelligence officials. Law and policy support such revocations, but as the swift and negative reaction in Washington showed, the president must take a nuanced approach. The legal framework for security clearances was charted by a 1988 Supreme Court decision, Department of the Navy v. Egan. The justices noted that a president has absolute power to grant, deny or revoke access to classified information. This authority is inherent in his role as commander in chief. The court ruled that the president could form...