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.