Senators will be entirely justified when they vote later today to disapprove of President Trump’s (mis)use of supposed “emergency” powers to spend funds for a border wall that Congress did not appropriate for that purpose.

The only shame is that the votes won't be there to override his promised veto. Actually, if Senate Republicans had appropriate self-respect, Trump’s reported treatment of the vote as a “loyalty” test should make them more, not less, willing to cross him. They owe loyalty, not to Trump, but to the Constitution and laws of the United States, and they ought to teach Trump that lesson.

Trump’s assertion of emergency authority is a usurpation of Congress's exclusive power to appropriate federal money. Yes, Congress delegated some of that power to the president in certain emergency situations, but that delegation of power is neither open-ended nor a blank check. The default assumption in any gray area should be that the president lacks such power.

Nobody is suggesting that the 1976 National Emergencies Act is facially unconstitutional. Instead, Trump’s use of that act, as applied, runs afoul of the interplay between the Constitution and the terms of the statute itself.

Perhaps the best explanation of this interplay came a month ago from National Review’s David French. The 1976 statute specifically applies only to a situation that “requires the use of the armed forces.” This one doesn’t. It would use funds meant for military construction to support a civilian enforcement effort. Right there, the president’s authority ceases.

This means that it matters not how someone does or doesn’t define what qualifies as a “crisis,” much less an “emergency.” Some of us would argue that the border issues present only “problems” or “serious challenges,” but not an emergency; but the point is, that judgment is immaterial. No subjective judgments like those are needed. This isn’t a project that involves the armed services, so the president has no emergency authority.

As I have argued previously, the spirit, intent, and tenor of the Constitution also clearly work against Trump here. Even Alexander Hamilton, the founder most likely to support expansive executive power, argued in the Federalist Papers that Congress must retain clear spending authority over the military. In fact, he said that Congress is not even “at liberty” to make open-ended delegations of such power to the president, because Congress has an especially important role in providing direct and deliberative congressional oversight of military funds.

For the president to use military funds for a nonmilitary purpose, without congressional appropriation, amounts to an abuse of our constitutional system. If a liberal Democratic president were asserting such authority, every Republican in the Senate would surely oppose it. If they do not likewise oppose Trump, they will be putting partisanship above their constitutional obligations, and thus abusing the loyalty they owe to the American people.