Given the epidemic levels of sexual violence and the widespread availability of increasingly graphic pornography in the United States, it is not surprising that researchers and activists have tried to answer the question of whether there is a connection between men's use of pornography and sexual violence. Since legal controls on sexually explicit material began to loosen dramatically in the 1970s and the issue attained a new visibility, a variety of different methods have been used to try to answer that question, or at least provide clues to the answer. After two decades of research, there is little consensus, not only as to that answer but as to definitions of terms, appropriate methods of investigation, or even how to frame the question. This essay will attempt to highlight the most relevant aspects of these disputes and reach tentative conclusions that can guide people working in the field.

Two terms often used in common parlance for sexually explicit material---obscene and indecent---have specific meanings in the law. "Obscenity" is that category of sexual material that the courts have deemed to be outside full protection of the First Amendment and subject to regulation by the state. Obscene material is defined as that which appeals to the prurient interest in sex, depicts sexual conduct in a patently offensive manner, and lacks serious literary, artistic, political, or scientific value ( Miller v. California, 1973). "Indecency" is a term from broadcasting (radio and over-the-air television) that defines an even broader category that can be regulated -- language or material that, in context, depicts or describes, in terms patently offensive as measured by contemporary community broadcast standards for the broadcast medium, sexual or excretory organs or activities ( Federal Communications Commission, 2004).

The term used most often in the public debate over sexually explicit material is "pornography," which is not rooted in law and has no commonly accepted definition. It is sometimes used as a generic term for commercially produced sexually explicit books, magazines, movies, and Internet sites, with a distinction commonly made between soft-core (nudity with limited sexual activity that does not include penetration) and hard-core (graphic images of actual, not simulated, sexual activity including penetration). In other contexts the term is juxtaposed to erotica, which typically is defined as material that depicts sexual behavior in a context of mutuality and respect. In that dichotomy, pornography is defined as material depicting sex in a context of domination or degradation. In many laboratory studies of pornography's effects, three categories of pornography are created: overtly violent; non-violent but degrading; and sexually explicit but neither violent nor degrading.

A separate category is child pornography -- material that is either made using children or, in the digital age, made through the use of technology that makes it appear the sexual activity uses children. The former is illegal without question ( New York v. Ferber, 1982); the status of the second remains uncertain but, for the moment, legal ( Ashcroft v. Free Speech Coalition, 2002).

The legal status of pornography using adults depends not only on the nature of the material, but also on the community and the political climate. Much of what is sold in pornography shops in the United States potentially fits the definition of obscenity, but in most jurisdictions prosecutors choose not to initiate cases. The same obscenity laws apply to the genres of lesbian or gay pornography. Those genres raise specific issues that will not be taken up here, and for the remainder of this essay, "pornography" will be used to refer to graphic, sexually explicit materials using adults engaged primarily in heterosexual sex, which makes up the bulk of the market.

If the question about the connection between pornography and violence is constructed simplistically -- "Does pornography cause rape?" -- the answer is clearly no. Since some men who use pornography don't rape, and some men who rape don't use pornography, pornography is neither a necessary nor sufficient condition for rape. There is no way to make a convincing claim that pornography is, as the lawyers say, an "if not but for" cause -- "if not but for the use of pornography, this man would not have raped."