Presidential pardon power is extraordinary, but it is not limitless. For the past 25 years, the Supreme Court has been reading federal grants of power like the Commerce Clause and the Necessary and Proper Clause more narrowly than at any time since 1937. The court should be just as strict in giving the pardon power only its original public meaning.

Mr. Trump did not have the constitutional power to obstruct justice by failing to faithfully execute the law through pardons of associates like Mr. Bannon, who could potentially testify against him. The Constitution and its amendments work like a giant power of attorney by which the founding generation, and their successors, We the People, have delegated certain limited and enumerated powers to the president, Congress, the federal courts and the states. The president is empowered to take care that the laws be faithfully executed and not to break them.