Among the tropes for restriction (somewhat overlapping) are protection of children, preservation of morals, protection of domestic industry, strengthening of national identity, protection of religious...

Among the tropes for restriction (somewhat overlapping) are protection of children, preservation of morals, protection of domestic industry, strengthening of national identity, protection of religious beliefs or a favored church, and avoidance of sectarian violence (Bollinger, 1976, 1991).