If Donald Trump is elected president, there are lots of things he has promised to do that would require an act of Congress. Barring immigration from Muslim nations — as a way to keep Muslims out of the U.S. — is probably not among them.
The nation's immigration laws give enormous power to the president to determine who and how many immigrants to allow into the U.S. And experts largely agree that if Trump, the presumptive Republican nominee, wanted to ban immigration from certain nations to keep out Muslim newcomers as he has proposed, he could probably do so.
"I think there is good reason to believe he has ample authority to exclude, for at least some period of time, anyone he wants," said Muzaffar Chishti, a lawyer and director of the Migration Policy Institute's office at the New York University law school. "There is an operational aspect to this that makes it absolutely clear that the president has the authority to do what Mr. Trump suggests."