Is President Trump acting beyond the constraints of the American constitution?

If he is, the U.S.A. is a nation-state that does not have the right to determine who can legally pass its boarders. Do all countries lack that constitutional right? Or has a custom arisen that permits anyone who wants to enter the U.S.A. to do so, and to denigrate anyone with the temerity to say that they can’t.

What’s below I copied from an online journal “The New” by a Mr. Cassidy. I can’t locate a date for it; so far I can see only a time,”  01:48 P.M.”

“Americans severely misjudged the authoritarians,” Umair Haque, a consultant and social-media maven, commented on Twitter on Saturday night. “But the authoritarians, it seems, also severely misjudged Americans.” Yes, they did, and this weekend’s events offered a bit of hope to everybody alarmed by Donald Trump. Saving America from the most unhinged and least qualified figure ever to occupy the Oval Office may well require a long and bitter fight. But a couple of early markers have been put down. The new President is not beyond the law. And many Americans will not stand by quietly as he traduces their country’s values, threatens its democracy, and destroys its reputation around the world…