As the fun of the entry ban continues, I thought I might point out some case law. Not my normal thing, but I know a bit about the subject.
Trump made waves during the campaign announcing his desire to ban all Muslims from entering the country-- a promise so wild and blatantly unconstitutional that Mike Pence, back before he had to toe the Trump line, couldn't stomach it. Yup, Mike Pence's description was "offensive and unconstitutional."
Trump changed the policy from a ban on Muslims to a ban on people from certain predominantly Muslim countries in order to try to escape the blatant unconstitutionality of his initial proposal.
Does anyone remember Kitzmiller v. Dover Area School District of Pennsylvania? This was the big one on the teaching of "intelligent design." The school district's rules required that "intelligent design" be taught alongside evolution. A parent objected on the grounds that "intelligent design" is nothing more than creationism dressed up in new clothes. As such, it is religion, and public schools cannot teach religion as science. Defenders of "intelligent design" argued that it was distinct from creationism. They were... somewhat undercut by the fact that the text they used (Of Pandas and People) went through a series of drafts. In old drafts, they gave a definition of "creation science" that was the same as the definition they eventually gave to "intelligent design." Why? Because it's the same fucking thing. Judge Jones gave the same assessment, but, ya' know, without the Carlin-speak. Stuffy lawyers...
See what I'm getting at here? Trump announced his intention to ban Muslims from entering the country. Even people like Mike Pence say no fucking way. Trump changes the policy to a ban on people from predominantly Muslim countries. And just over the weekend, Rudy Giuliani was going on tv, admitting that the whole thing was an attempt to get around the blatant unconstitutionality of a straight-up Muslim ban. Am I the only one thinking of Kitzmiller v. Dover?
Of course, the ban on migrants from certain predominantly Muslim countries isn't exactly, word-for-word, the same as a Muslim ban in the same way that the Pandas text interchanged "creation science" with "intelligent design." But, there's another nugget in the Kitzmiller ruling. It is based heavily on a controversial Supreme Court ruling (Kitzmiller wasn't a Supreme Court case)-- Lemon v. Kurtzman. Take a course on First Amendment law, and this one gets drilled into your fucking skull. Conservatives hate hate hate hate hate hate hate hate hate this ruling, but it has never been overturned. Why do they hate it so much? Figure it out from this. It is basically a test of whether or not a policy violates the establishment clause of the First Amendment. It is a three-pronged test: 1) does the policy have a purpose that is religious, 2) does the policy have an effect that is religious, or 3) does it promote excessive government entanglement in religion? Hit any prong, and the law violates the establishment clause of the First Amendment.
You can see why the "intelligent design" thing failed the "Lemon test" miserably. You can also see why conservatives don't like Lemon v. Kurtzman. Conservatives these days are basically motivated largely by religion. If your goal is to enact policies motivated by religion, a Supreme Court ruling that tells you that you can't enact stuff that is basically sectarian religious law is kind of a problem for you.
Lemon v. Kurtzman is not the case that will come to most lawyers' minds these days because the entry ban is more about free exercise than the establishment clause, but the logic of the test is an interesting analog, particularly in reference to Kitzmiller v. Dover. The change from a ban on all Muslims to a ban on entry from specific countries looks a lot to me like the textbook revision thing in Kitzmiller v. Dover. It clearly demonstrates that the purpose is religious discrimination, creating an analogy to the first prong of the Lemon test, as in Kitzmiller v. Dover, and the predominance of Islam in the countries chosen creates an effect of bias against Islam, creating an analog to the second prong.
Anyway, I'm just a lowly Ph.D. I'm sure a real lawyer would say I'm doing this wrong. (Lemon v. Kurtzman was about the establishment clause, not the free exercise clause, etc.). Fuck 'em. My students have heard me complain about law as a discipline enough anyway. The Constitution is an absurdly vague document, and anyone reading it is almost assured to engage in motivated reasoning. Is "the Lemon test" from Lemon v. Kurtzman the proper way to interpret the First Amendment? Fuck if I know. I'm just spit-balling.
The chaos continues...