We all pretty much expect that anytime Potus decides to do something, someone will go running to the 9th Circuit and file a lawsuit. It happens time and time again. I found this (pic related) Bill Mitchell tweet interesting, so I did a quick search and found the following article.
http://theconversation.com/if-trump-declares-a-national-emergency-could-congress-or-the-courts-reverse-it-109752