In the case that a State or unit of local government issues an order that limits gatherings to a certain number of people pursuant to a national emergency declared by the President under the National Emergencies Act (
50 U.S.C. 1601 et seq.) or a similar State emergency declaration, the State or unit of local government may not discriminate in the enforcement of such order, in the case of persons who are exercising a right protected under the First Amendment.