Correction: An earlier version of this article twice gave an incorrect year for when O’Connor voted to uphold <i>Roe v. Wade</i>. Her decision came in 1992, not 1993. This version has been corrected.

Cary Franklin is a professor at the University of Texas School of Law.

Sisters in Law
How Sandra Day O’Connor and Ruth Bader Ginsburg Went to the Supreme Court and Changed the World

By Linda Hirshman

Harper. 390 pp. $28.99

When the Supreme Court held in June that same-sex couples have a constitutional right to marry, the moment must have been doubly sweet for Justice Ruth Bader Ginsburg. As a lawyer in the 1970s, she brought and won a groundbreaking series of sex-discrimination cases that helped strip marriage of its officially gendered roles — a change that paved the way for the claims of gay and lesbian couples. Then there was the simple fact that she was not in the dissent. Ginsburg’s passionate dissents have earned her a place among the great dissenters in Supreme Court history. But it must have been nice for the woman who, as a result, has become known as Notorious R.B.G. just to join a prominent majority opinion.

With a good nose for the big legal story of the moment, Linda Hirshman — author of “Victory” (2012), a popular account of the gay rights movement — is back, this time with “Sisters in Law,” a joint biography of Ginsburg and Sandra Day O’Connor. Ginsburg is attracting a lot of attention these days, especially from the young and hip (who have emblazoned all manner of dry goods with her likeness and blanketed D.C. with “Can’t Spell Truth Without Ruth” stickers). But it’s not just the Ginsburgian subject matter that makes Hirshman’s book seem so vital. “Sisters in Law” tells the life stories of the nation’s first female justices, but it is as much about how we got to the present juncture with respect to women’s legal rights.

The book begins at the Day family’s Lazy B Ranch, where a young Sandra fixed flat truck tires and grew up practical and independent, and in 1930s Brooklyn, where Kiki Bader excelled in the classroom. You probably don’t get to be a groundbreaking woman on the Supreme Court without leading an interesting life, and neither O’Connor nor Ginsburg disappoints. O’Connor made a name for herself in the Arizona Republican Party as a state legislator and judge; she was an energetic networker who seems to have cooked for half of Phoenix. Ginsburg was a law professor who looked into the issue of sex discrimination at the behest of her students and within a few years had become the nation’s top litigator in the area, winning a string of Supreme Court cases that fundamentally altered the court’s outlook on women’s rights.

The biographical stories are, by and large, not new, but one hardly minds because Hirshman tells them so well. (My favorite is her funny, then suddenly quite moving account of the day Ginsburg discovered she would be nominated to the court.) All of these stories are in the service of a larger project: explaining how the court went from condoning — and engaging in — sex discrimination to treating it as constitutionally prohibited.

No one is more responsible for this legal revolution than Ginsburg. When she began litigating cases, women were excluded from some of the nation’s top colleges, had trouble obtaining credit in their own names and could be fired from their jobs for becoming pregnant. Thousands of laws constrained Americans’ opportunities on the basis of sex. Ginsburg developed a simple but powerful argument against these laws. She argued that the Constitution’s equal-protection guarantee forbids the state to push men and women into traditional sex roles. Over the course of a decade, she convinced the court that laws that reflect or reinforce the stereotypical notion that men will act as society’s breadwinners and women as its caregivers violate our nation’s deep commitment to equality. Today, this anti-stereotyping approach (though incompletely realized) is the law of the land.

Hirshman argues that O’Connor, too, played a critical, if less-celebrated, role in the development of sex-discrimination law. In the 1980s, when the court shifted rightward, it was O’Connor who prevented it from backsliding — or backsliding too far. When a Mississippi man sued after being denied admission to a public women’s nursing school, it was O’Connor who declared the sex-based exclusion unconstitutional, finding that it reinforced “fixed notions concerning the roles and abilities of males and females.” In 1992, when many believed that the court would overturn Roe v. Wade, O’Connor not only helped to preserve the decision but also expanded the constitutional basis for reproductive rights by holding that a spousal-notification requirement violated women’s equality.

Much has changed in the intervening decades. In 2006, O’Connor was replaced by Circuit Court Judge Samuel Alito, the very judge whose arguments for upholding the spousal-notification requirement she rejected in 1992. (Last year, in the Hobby Lobby case, Alito expressed considerable skepticism that “gender equality” — a phrase he put in quotes — was a sufficiently compelling state interest to justify requiring religious employers to provide health insurance coverage for contraception.) Ginsburg soldiers on, but she rarely commands majorities in cases involving gender and reproduction.

Part of what makes Hirshman such a likable writer — in addition to her wit and ability to explain the law succinctly without dumbing it down — is her optimism. “Sisters in Law” ends with a call for more female justices. Surely, Hirshman concludes, judges who have experienced being female in American society will be more responsive to sex-equality concerns than the Roberts court has been.

It’s true that the court’s female justices have voted in favor of plaintiffs in sex-discrimination and reproductive rights cases more often than their male colleagues. But female judges are not uniformly more sympathetic than male judges to such plaintiffs. Indeed, there were women on the long list to replace O’Connor who were decidedly less sympathetic in this regard than the average male judge. In these polarized times, the party of the appointing president is probably a better predictor than sex of a justice’s disposition toward sex-equality claims.

The book leaves one feeling optimistic nonetheless. Here is a biography of two women that focuses centrally on their work. (I have no doubt O’Connor loves her children, but their names don’t appear in the book.) This alone is cause for celebration; bookstore shelves aren’t exactly crowded with biographies of great women at work. How much better that the work in question seeks to enable many more women (and men) to carve out their own life stories unconstrained by sex-role stereotypes.