Even John Yoo, author of torture-approving memos in Bush’s Justice Department, thinks Trump is overstepping the limits on what presidents can do.

Article II of the Constitution vests the president with “the executive power,” but does not define it. Most of the Constitution instead limits that power, as with the president’s duty “to take care that the laws are faithfully executed,” or divides that power with Congress, as with making treaties or appointing Supreme Court justices.

Hamilton argued that good government and “energy in the executive” went hand in hand. In The Federalist No. 70, he wrote that the framers, to encourage “decision, activity, secrecy and dispatch,” entrusted the executive power in a unified branch headed by a single person, the president.

Woo considers himself a Hamiltonian.

But even I have grave concerns about Mr. Trump’s uses of presidential power.

During the campaign, Mr. Trump gave little sign that he understood the constitutional roles of the three branches, as when he promised to appoint justices to the Supreme Court who would investigate Hillary Clinton. (Judge Neil M. Gorsuch will not see this as part of his job description.) In his Inaugural Address, Mr. Trump did not acknowledge that his highest responsibility, as demanded by his oath of office, is to “preserve, protect and defend the Constitution.” Instead, he declared his duty to represent the wishes of the people and end “American carnage,” seemingly without any constitutional restraint.

While my robust vision of the presidency supports some of Mr. Trump’s early executive acts — presidents have the power to terminate international agreements like the Trans-Pacific Partnership, for example — others are more dubious. Take his order to build a wall along the border with Mexico, and his suggestion that he will tax Mexican imports or currency transfers to pay for it. The president has no constitutional authority over border control, which the Supreme Court has long found rests in the hands of Congress. Under Article I of the Constitution, only Congress can fund the construction of a wall, a fence or even a walking path along the border. And the president cannot slap a tax or tariff on Mexican imports without Congress.

Well…if he can’t, maybe one of his helpers can? Steve Bannon for instance?

Nor can Mr. Trump pull the United States out of Nafta, because Congress made the deal with Mexico and Canada by statute. Presidents have no authority to cancel tariff and trade laws unilaterally.

Immigration has driven Mr. Trump even deeper into the constitutional thickets. Even though his executive order halting immigration from seven Muslim nations makes for bad policy, I believe it falls within the law. But after the order was issued, his adviser Rudolph Giuliani disclosed that Mr. Trump had initially asked for “a Muslim ban,” which would most likely violate the Constitution’s protection for freedom of religion or its prohibition on the state establishment of religion, or both — no mean feat. Had Mr. Trump taken advantage of the resources of the executive branch as a whole, not just a few White House advisers, he would not have rushed out an ill-conceived policy made vulnerable to judicial challenge.

But where’s the fun in that? Trump wants the fun he imagines goes with the job. He couldn’t care less what the Constitution says…despite having sworn that oath.

A successful president need not have a degree in constitutional law. But he should understand the Constitution’s grant of executive power.

He should at least have read the damn thing. I strongly doubt that Trump ever has.