The principal issue in this case is the validity of the Illinois obscenity statute, considered in light of Miller v. California, 413 U. S. 15 (1973). There we reaffirmed numerous prior decisions declaring that "obscene material is unprotected by the First Amendment," id., at 23; but acknowledging "the inherent dangers of undertaking to regulate any form of expression," ibid., we recognized that official regulation must be limited to "works which depict or describe sexual conduct" and that such conduct "must be specifically defined by the applicable state law, as written or authoritatively construed." Id., at 24. Basic guidelines for the trier of fact, along with more specific suggestions, were then offered: