President Donald Trump’s “extreme vetting” policy has been attacked by the Left since he signed an executive order days after his Inauguration as a temporary measure. On Sept. 27, 2017, the president replaced all previous versions of the temporary measure with Presidential Proclamation 9645, a permanent policy to vet people entering this country, restricting entry from eight terror-prone nations. Challengers say that immigration law does not grant the president such authority, and that even if it did, then this policy would violate the First Amendment’s Establishment Clause because it establishes a national religion that discriminates against Muslims. In his amicus brief at the Supreme Court, the ACRU’s Ken Klukowski argues why Proclamation 9645 is fully consistent with the Constitution.