A constant refrain we now hear is that President Trump’s order to finance the wall is “unconstitutional” and “violates the separation of powers.” That is not the case. Richard H. Pildes, a professor of constitutional law at New York University, wrote on March 14 the clarifying article, “How the Supreme Court Weakened Congress on Emergency Declarations.”

Here are his salient points:

Trump’s declaration of a national emergency to build the wall derives from that singular authority in the National Emergencies Act (NEA), passed by Congress in l976. Since then, presidents have resorted to the NEA 58 times. In each case, the president—Democrat and Republican—spent funds not appropriated by Congress and the Supreme Court did not overturn the action. Pildes notes, “Courts are uncomfortable when asked to second-guess presidential judgments in areas such as national security, foreign affairs and emergencies.” The courts are not experts on these matters.

Pildes cites the key Supreme Court decision, Immigration and Naturalization Service v. Chadha, which declared, he says, that “legislative vetoes are unconstitutional”—including vetoes of actions under the National Emergencies Act, the basis on which Trump acted.