If the Supreme Court struck down Congress’ attempt to protect religious liberties in the Religious Freedom Restoration Act, why wouldn’t it just do the same thing with RLUIPA?
Congress has different constitutional sources for its authority. If the Supreme Court denies it the power to create a law under one source, Congress may still be able to accomplish its goal using a different source. Congress justified its passage of RFRA under a section of the 14th Amendment that gives it the power to pass laws deemed necessary to protect the liberties ensured by that amendment, which would include the First Amendment’s guarantee of “free exercise of religion.” The Court held that under that section Congress was only permitted to develop laws that would enforce the standard of protection deemed necessary by the Court itself, as opposed to the stricter general standard embodied in RFRA.
RLUIPA’s justification was rooted in Congress’ power to regulate matters touching on interstate commerce. The Supreme Court has only rarely overturned congressional acts based on the interstate-commerce clause, so it is possible (though far from a certainty) that the Court would find a sufficient tie to interstate commerce to justify Congress in creating RLUIPA. It is important to note that even if the Court finds that Congress acted from the proper source of authority, the act might still be found to violate the establishment clause and therefore be unconstitutional.