Trump could have saved himself a lot of wasted legal hassling if he did what some of his advisors told him to do-- use Obama's list of 7 countries which train and indoctrinate terrorists to vet and exclude potential terrorists no matter where they came. This way a British, French, Belgium, Arab or Dutch citizen who has travelled to Libya one or more times will be vetted as a potential terrorist. So the Manchester bomber who was a British citizen, but who travelled to Libya would be vetted. Even if the Supreme Court drops the temporary stay obtained by Hawaii and other states, Trump's approach will be challenged until it is "fixed"-- remember, the Marines and Seals were ready to sue to get in Muslims who helped them until the temporary stay. In fact, once Trump's stay goes into effect unless it is fixed, there will be more challenges and more wasted legal proceedings.