See Robin West’s important new article Download west_consent.pdf critiquing the legitimation function that consent plays for liberal understandings of sex and law. West defends consent as the border between criminal and non-criminal sex, but argues that relying solely on this line can render political and normative critique invisible. She focuses her analysis on unwanted, unwelcome consensual sex, and calls on legal theorists for pay more attention to consensual sexual harms and their relation to law.
In general, my own work has tended more to critique the over-regulation of sexual practices. In a fairly infamous British case cited by the Supreme Court in Lawrence, known as the Spanner case, what had clearly been consensual S&M practices were found to be properly criminalized. I find the critique of the uniqueness that Anglo-American law has traditionally assigned to issues involving sexuality (think obscenity as a category outside First Amendment protection) to be largely persuasive. Robin and I have had different emphases in our work, but I think we largely agree on where the important lines should be drawn. And my respect for the quality of her scholarship is enormous.