Yeah, I don't remember the details and someone correct me if I am wrong but Obama basically did the same thing that Trump is trying to do right now. I leterally see no legal reason for them to shoot this thing down. All they have is "We don't like it".
I would love to see Trump shut all immigration down then. I mean for all the courts know, the POTUS could have intel that a nuclear bomb scientist is coming over and that guy is the one that knows how to assemble it or something. Unless the judge making this ruling gets more info on national security than what Trump gets something is wrong with our system if the POTUS is able to be overruled by a judge when it comes to national security issues.