The Constitution does not give the judiciary the power to make or execute immigration and naturalization law and regulation. That power is given explicitly to Congress which passed laws giving the President vast authority. For over 200 years the judiciary has properly deferred to the executive and legislative branches.
From a bar association article:
“The Court upheld congressional immigration laws and executive enforcement of those laws against a series of challenges, in spite of their patently discriminatory nature and lack of due process guarantees for noncitizens. The Court repeatedly suggested that this federal power flowed from the federal government’s prerogative to control foreign affairs.
From the late 19th century through the present day, the Supreme Court has upheld almost every federal immigration regulation against constitutional challenge, citing Congress’s plenary power in this area. As Justice Kennedy wrote in the 2012 decision in Arizona v. United States:
The Government of the United States has broad, undoubted power over the subject of immigration and the status of aliens. … This authority rests, in part, on the National Government’s constitutional power to “establish an uniform Rule of Naturalization,” U. S. Const., Art. I, §8, cl. 4, and its inherent power as sovereign to control and conduct relations with foreign nations….”
Nowhere do the laws or the Constitution give overseas aliens a right to immigrate to the US or due process rights to contest immigration decisions in US courts.
From a NYT article,
A key part of immigration law does give the president broad power. It says, “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.”
That’s very broad.
The lower court judges are advancing a judicial power grab asserting their authority to review decisions in areas where they are not given any Constitutional authority to do so. No previous Supreme Court decision has ever held the First Amendment prohibits consideration of religion or nationality in immigration regulations. We had a national quota system from the 1920s to 1960s, we preferentially admitted Cubans, Vietnamese, and Russian Jews- all upheld as perfectly legal.
Finally, while the Courts often look to statements outside a law or regulation to clarify intent when there is ambiguity, this is being expanded and warped to arrive at the doctrine that the letter of the order or regulation is secondary to the motivation of the president in issuing it and the Courts get to rule on that intent as opposed to what the rule actually says. So no matter how the order is changed, any statement Trump ever made can be introduced to have it overturned. That is a recipe for judicial tyranny.
At this point many opponents of the travel ban don’t care. They don’t see beyond their immediate victory to a judiciary stacked with Trump appointees who stymie every action of a newly elected Democratic President who “rule from the bench” based on the precedent now being set.