OPINION: Disapprove

It’s not going to be easy for Senate Republicans to vote to disapprove of President Trump’s declaration of emergency at the border. They should do it, nonetheless, on principle and out of institutional self-respect.

At the conclusion of the showdown over funding for his border wall, Trump announced that, on top of the $1.3 billion Congress appropriated, he would tap roughly $3 billion from other sources and declare an emergency to get access to another $3.6 billion in military construction funds.

The spending is sequenced so the national-emergency funds come...