The Ninth Circuit,  the most overturned circuit court in the US, has ruled that the President didn't justify his EO well enough for them.  But the law doesn't require him to justify squat.  8 USC 1182(f) "Suspension of entry or imposition of restrictions by President Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate...."  Too bad the three judge panel didn't actually follow the law as written.