Plaintiffs: The Metropolitan Washington Airports Authority shouldn’t be using revenue from Dulles airport’s toll road to pay for a new Metrorail line (scheduled for completion in 2020) connecting Dulles to D.C. Metro. Indeed, the structure of the airport authority violates the nondelegation doctrine, the Guarantee Clause, and the Appointments Clause. Fourth Circuit: Not so. The authority is not a federal entity, so it is not subject to the limitations of the Constitution. Statutory claims fail, too.