How Sex Became a Civil Liberty, by Leigh Ann Wheeler, Oxford University Press, 352 pp., $34.95.

When it comes to Americans' understanding of sexual privacy and public sexual expression, most of us are effectively members of the American Civil Liberties Union. This is so even for people who carry no card, pay no dues, and—if such a thing were possible—have never even heard of the organization.

That's the takeaway from How Sex Became a Civil Liberty, Leigh Ann Wheeler's dense but fascinating account of the ACLU's wildly successful efforts, since its founding almost 100 years ago, to bring sex under the purview of the Bill of Rights. Wheeler, a Binghamton University historian, could have stuck with a wonky narrative about a long march of law and jurisprudence. Instead, she's taken what she calls an "empathic" approach. She has combed vast archives, including personal correspondence of the ACLU's founders and decades of files from the national office and local affiliates.

From these papers she has assembled a story about men and women working through their own sexual passions and contradictions as they shaped a legal and political practice for the entire country. She reveals how activists pushed, slouched, and pushed some more to arm their fellow citizens with sexual rights, even as those rights provoked further conflicts, including among ACLUers themselves.

Wheeler's story starts in the 1920s, as young, educated men and women flocked to Greenwich Village to partake of a modernist cultural revolution with heady new ideas about the nature and purpose of sex. One of these migrants was Roger Baldwin. As a 12- or 13-year-old in the 1890s, he had been seduced by his family's Irish servant. He'd spent the next few years having sex with her, learning, as he put it, "everything that was to be known, even how to prevent getting her pregnant."

In the Village, Baldwin met Madeleine Zabriskie Doty, who had spent her youth wondering if she was physically attracted to women rather than men. By the 1920s, she was in love with Baldwin. The couple wed in the new style, sans ring or vows. And Baldwin founded the ACLU.

Baldwin was a proponent of "free love," believing that living a "creative life" required "many loves shared together openly, honestly, and joyously." Like other women she knew, Doty agreed that her husband could have lovers, but she was reluctant to take her own. She became accidentally pregnant at least once by Baldwin. She managed to end the pregnancy, though it's not clear how.

Though Doty, Baldwin, and other founding ACLUers fought Mars-versus-Venus battles over sex and sex roles, they sought detente by jointly taking up the cause of birth control education. All had a gut understanding of how desperately men and women wanted this teaching. But the so-called Comstock Law of 1873 banned distribution of this information through the mail, calling it obscenity. And the federal statute had inspired "little Comstock laws" in many states that outlawed even public discussion of contraception. One of the ACLU's first campaigns, beginning in the 1920s, asked courts to apply the First Amendment to lectures, pamphlets, and ads on such topics as the rhythm method and condoms.

The early ACLU leadership vacationed together at Martha's Vineyard. On isolated beaches there, many practiced nudism. Nudists today are largely winked at if not ignored. But in the 1930s and '40s, they saw themselves as an avant-garde movement. Going undressed, they believed, would strengthen democracy by challenging the class distinctions so visible in clothing. They also thought the sight of people casually strolling in the buff would cool the frisson of obscenity.

In 1934, ACLU started not just defending nudists' right to publish material depicting them and their families naked, but to gather that way in private. The organization thus entered a new arena. Heretofore it had defended speech deemed sexually inappropriate. Now it spoke up for acts in the privacy of the bedroom—including, a generation later, homosexuals' right to commit "sodomy."

Until the late 1960s, as Wheeler tells it, the ACLU occupied an easy moral high ground when it came to sex and the First Amendment. Exploiting the tenets of an exploding consumer culture after World War II, the group successfully pushed the notion that everyone should be able to see and read anything they pleased, even if the speech in question was commercial and cheesy.

Take Playboy. During its consumerist period, the ACLU befriended Hugh Hefner and his enterprise. In 1966, the organization's Illinois affiliate even got Hef's subscriber list and sent out a membership solicitation. It told the overwhelmingly male recipients that "Sophisticated people like yourself are not afraid to read whatever magazine or book you want to," including those with pictures "of a divine figure with smasheroo legs."

Then things got dicey.

By the time of the Playboy mailing, Second Wave feminism was taking up where people like Madeleine Zabriskie Doty and other First Wavers had left off 50 years earlier in the Village. In the early 1970s, the ACLU staunchly supported abortion rights, as did Hefner and his magazine. At the same time, ACLU members were arguing among themselves about other civil liberties, liberties that were starting to seem sticky when framed in the lens of gender rights.

Rape-shield laws, for example, aimed to prevent defense lawyers from using accusers' prior sexual histories to bash their credibility. Feminists enthusiastically promoted rape-shielding. But old-school ACLUers remembered the organization's earlier advocacy for black men in the South who'd been accused of rape by white women—women the ACLU had been happy to discredit by claiming they'd been promiscuous in the past.

New controversies played out alongside good old-fashioned theater. In 1972 feminists in the Chicago Women's Liberation Union—some of them also ACLU members—crashed an ACLU fundraiser held at the Playboy Mansion. The fete was so Hefner-inflected that it included nude swimming at 4 a.m. The women's liberationists bounded in with pinups of men in bunny suits, featuring slogans such as "He's got a nice ass but he's kind of dumb."

Today those Playboy-hating days, like Playboy itself, are largely passé. Inside the organization, the ACLU has since weathered further First Amendment controversies about everything from sexual harassment laws to Dworkin-McKinnonesque moves to ban revoltingly violent porn.

Through thick and thin, Wheeler believes, the ACLU's support of unfettered sexual expression has tended to polarize the public. But the trend has been on the organization's side. Opinion polls show that most Americans today oppose laws against gay sex, support legal abortion, and condemn censorship.

How did the country come to these card-carrying positions? Through the intrepid and conflicted men and women of the early ACLU, Wheeler argues. By working out their own issues in an organizational and political sphere, they stretched their sexual revolution clear through the 20th century and into 21st.