But a program like NSEERS would likely pass constitutional muster before a judge, multiple experts said, in part because it already has. The system was never struck down by a court in the nearly nine years it was in place.

Jonathan Turley, a law professor at George Washington University, said Wednesday that “a president’s power is at its apex at the nation’s borders” and that the Supreme Court has “consistently reaffirmed the power of the president to control the entry and exit from the country as a matter of national security.” Such precedent, he said would give Trump’s administration a decided advantage in any litigation.

Immigration law would afford the government special advantages, Temple University international law professor Peter Spiro said, because it exists in a “parallel universe” where many of the constitutional protections afforded in other legal situations do not apply. He said “discrimination on the basis of nationality is something that, again, one finds all over the immigration law, and in a nonimmigration context would almost certainly not withstand the equal-protection challenges.”

Despite its ability to pass constitutional muster, Spiro is no fan of the NSEERS, which he called “a terrible policy” and “a silly program in a lot of ways.”