You are also correct. Somehow this seems to be something right in between the Fed and the local authorities. This is probably going to lead to a lot of confusion. I would like to point out though, that Sessions is a law enforcer, not a law maker. Perhaps this is his way of saying “look, Congress, you need to get your act together and decide what you want to do. I am done being the one to enforce an Obama era policy.” The Obama department of justice was being used to provide policy guidance in a way to go around Congress. I think Sessions, who has already said he thinks Congress should act on this matter, it’s simply fed up with enforcing an Obama era policy, and has acted within limits of his power to make an issue of this.