While it’s uncertain whether President Donald Trump will declare a national state of emergency, doing so wouldn’t be unprecedented, as the U.S. still operates under 31 such orders. Whether his actions would be warranted, or legal, is also hotly debated. Trump renewed his threat Thursday, saying he would almost “definitely” declare a national state of emergency if a deal isn’t reached with Democrats in Congress to end a stalemate over funding a U.S.-Mexico border wall. The federal government shutdown caused by the dispute is now in its 20th day. “If this doesn’t work out, probably I will do it,” he...