How would you feel if your partner brought pornography home? That was the question history professor Leigh Ann Wheeler asked her students 15 years ago at the University of Minnesota. Almost every female student responded that she was "uncomfortable" with pornography, but that she wouldn't violate her partner's right to free speech by prohibiting it.

Wheeler, now a professor at Binghamton University, found this curious. In her new book, "How Sex Became a Civil Liberty," she writes, "At the end of the 20th century, these students equated criticizing pornography and exercising control over their private space with advocating censorship, eliding, in the process, critical distinctions between private conduct and state action." Just a few decades earlier it was unthinkable that sexual rights could be protected by the Constitution. But here her students were conflating "personal opinions, private relationships, and civil liberties," she says.

How exactly did this happen? Wheeler attributes much of this to the American Civil Liberties Union. "The ACLU played a pivotal role in drawing the parameters of this nation's disputes over sexuality," she writes, and much of the book focuses on the organization's influential role. It's wonky stuff, to be sure, but the book does have a scandalous side: Wheeler takes a look at how the freewheeling sexual experimentation of the ACLU's founding members in 1920 shaped the organization's early political agenda surround...