Why national emergencies are usually declared

Why it matters: Most experts agree that Trump’s use of a national emergency would be a legally questionable use of emergency powers. The Brennan Center for Justice has found 123 emergency powers the president can invoke. If Trump does declare a national emergency to build his border wall, he would likely use one or two powers related to military construction.

Those emergency construction powers have only been used twice: by George H.W. Bush during the Gulf War, and then by George W. Bush after 9/11. Those orders aren’t listed in the graphic because they were just amendments to earlier emergency declarations.