Let’s start with the law.
The president of the United States has power to bar “any class of aliens” both as immigrants and as nonimmigrants and to impose on their ordinary comings and goings “any restrictions he may deem appropriate.”
That’s the language of the U.S. Code, the law of the land as enacted by Congress, under Congress’ own constitutional power over immigration and naturalization.
Presidential power is never absolute, of course. It’s always subject to the Constitution. Many have argued that Trump's ban is unconstitutional because—as the president himself has repeatedly said—it’s intended to ban Muslims, and should be regarded as prohibited religious discrimination.
But here’s the problem for those making the argument: It’s firmly established U.S. law that the rights of the Constitution belong only to Americans. The U.S. Army can strip enemy combatants of weapons without offending the Second Amendment right to carry firearms. It can billet troops in private dwellings overseas without offending the Third Amendment. The NSA can intercept foreign communications without regard to the Fourth Amendment. The U.S. courts do not hear cases from foreign nationals who complain their due process rights under the Fifth Amendment somehow been infringed. And so through the gamut.
Where do foreign nationals then acquire their supposed First Amendment right to enter the United States without religious discrimination?
The answer offered by Judge Derrick Watson’s opinion is a judicial reach of a kind that might sound clever to the student editors of an academic law review—but that should worry all Americans in real life...