There is no precedent to support this claimed unreviewability, which runs contrary to the fundamental structure of our constitutional democracy. See Boumediene v. Bush, 553 U.S. 723, 765 (2008) (rejecting the idea that, even by congressional statute, Congress and the Executive could eliminate federal court habeas jurisdiction over enemy combatants, because the “political branches” lack “the power to switch the Constitution on or off at will”).

The pot calling the kettle black. It's a new situation, for sure, and we shouldn't expect either side to have a ton of authority but it's notable that probably the closest decision the States can point to is Boumediene, which really doesn't actually say what they want it to say. After all, unlike a habeas proceeding, which was certainly well within the ken of the Courts, the Executive and Legislative branches have never given any sort of discretion to the courts regarding immigration, and certainly not on the level of habeas proceedings.