Good question. Seattle district court judge James Robart certainly doesn't believe in following the written law. The 1952 law says the president has total authority to ban any immigrant or class of immigrants from entry to the United States. Judge Robart ignored this and forbade the president from barring immigration from seven Middle East countries. In short, the judge ruled in accordance with his personal political ideology and not in accordance with the law on the books. Plus the two plaintiff states clearly lacked standing to sue the federal government.
What's worse, the 9th Circuit court of appeals backed him up. So, we have the federal courts in the western part of the country making judgements based on personal prejudice rather than written law. I wonder what they were teaching in law school back when these so called judges were doing law school. Scary.
So much for the procedural argument. The substance of the issue is of only medium importance. We don't get all that many immigrants from the seven middle east countries in Trump's executive order. On the other hand, these seven countries are so screwed up from civil war or just plain collapse into failed states, that we cannot believe anything they tell us. We ought to be vetting immigrants to weed out criminals and select for people who will become loyal and productive members of American society. Vetting means contacting the authorities in the immigrant's home country to verify his name and home address, see how much schooling he has, see his police record, and so forth. This only works if the home country has authorities in charge. The seven countries on Trump's executive order are all so war torn that we cannot find the authorities, and even if we find someone who claims to be an authority in an enemy country like Iran or Syria, we suspect that they would lie to us. Surely an Iranian mullah who wanted to infiltrate an agent into the US would have no problem telling US authorities that "Yes Omar is a good boy, never been in trouble, good marks in school. Yada-Yada."
So, it's a twofer, the so called judges are wrong on the issues as well as procedures. Very scary.