i said all along that the way to beat the travel ban is to argue that it's ineffective in it's stated purpose, not that it discriminates due to religion. the president gets a lot of discretion; you have to basically prove he's acting irrationally, and so you must do so by taking his claim of needing the ban for national security seriously and then proceed to demonstrate that the ban does not in any way actually do this. they went after him with the wrong legal tactic last time and ultimately lost; this time, they're doing this right and should win.
they could stop the wall that way, too. again: if you want to challenge the president in court, you have to take what he says seriously to start off with. so, the wall is intended to stop migrants from entering without prior approval. a strong legal case can be made that this will not actually work, that it is in truth simply an irrational policy. the law can be struck down on review if you win this case. i'm not sure who gets standing in such a case, though.
http://www.cbc.ca/news/world/trump-travel-ban-partially-lifted-1.4464042