Blasphemy is generally understood as speech calculated and designed to transgress, or express contempt for, central religious beliefs. In older cases, blasphemy laws were upheld on the ground that they were designed to prevent the incitement of violence and therefore served the needs of society rather than religion. More recently, blasphemy statutes have been held to lack a secular purpose, and serve only to advance religion in violation of the Establishment Clause of the First Amendment.
The Supreme Court has held that it is not the business of the government to suppress real or imagined attacks upon a particular religious doctrine, whether they appear in publications, speeches, or motion pictures.
Brooklyn Institute of Arts and Sciences v. City of New York--Rudy Giuliani took offense at a work at the Brooklyn Museum of the Holy Virgin Mary which incorporated elephant dung. The City took action by trying to withhold funds and remove the museum from City land.
Burstyn v. Wilson--Burstyn challenged the NY State Board of Regents for banning his film because it was "sacrilegious."