It looks like there are a bunch of experienced folks who are implying that Trump's immigration order doesn't rise to the level of a necessary enhancement to national security.
If it lacks the justification, does Trump's EO have trump power over constitutional imperatives?
The courts will doubtless consider the scope of presidential freedom in defining for itself the meaning of the words "national security". The INA isn't limitless in its breadth and while the courts have traditionally granted wide discretion to the executive over issues of national security and immigration, they have intervened where they perceive over-reach - as the previous president discovered.
So where does the political judgement end and the rest of the law and the constitution begin? It's an interesting question where you have an executive arm determined to push the normal limits over the objections of the contemporaneous attorney general.