Two federal district court judges nevertheless blocked implementation of the new order this week, finding that it violates the First Amendment's establishment clause, which demands separation between church and state. Judge Derrick K. Watson relied on previous rulings that government actions "must have a primary secular purpose" as he rejected the national security rationale the Trump administration offered and concluded that Trump's transparent aim was "temporarily suspending the entry of Muslims." Watson used the president's previous calls for a Muslim ban, along with a variety of more recent statements from Trump associates, as evidence of Trump's discriminatory intent.
But as five judges on the U.S. Court of Appeals for the 9th Circuit pointed out, the Constitution expressly stipulates that Congress can set naturalization policy, and Congress did so in the Immigration and Nationality Act of 1952 — which delegates the president broad authority to "suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants." In the past, when the executive branch's use of that authority has conflicted with other constitutional principles, such as freedom of speech and freedom of association, courts have been deferential to the executive, acknowledging that immigration policy is a complex subject in which a variety of interests can and do motivate decisions and in which the courts should be wary of substituting their judgment for that of the political branches. In general, courts bow to the government as long as it provides "a facially legitimate and bona fide reason" to act.
Even using that deferential standard, critics could argue that the national security justifications the Trump administration has provided for its order are too thin; as a policy matter, the order lacks the support of logic or evidence. They could also argue that the establishment-clause interests are so strong that the courts must try to ascertain the president's authentic motivations, as they have in other contexts.
But judges may well flinch at the prospect of conducting a trial to ferret out the president's intentions and to craft new boundaries for the nation's immigration policy, restrictions that could be binding on Trump's successors, too. The critics have a strong case that the president's executive order is self-defeating and offensive to American values. But it is far from clear that the courts will deem it illegal, too.