When, in 1981, Ronald Reagan nominated Sandra Day O’Connor to the Supreme Court, her views on abortion became a source of intense speculation. Photograph by Horst P. Horst / Condé Nast / Getty

In many U.S. states, abortion was once a crime. It may be again, if Ruth Bader Ginsburg, who just finished her third fight with cancer, leaves the Supreme Court during the Trump Presidency. If, as is widely speculated, Trump nominates Judge Amy Coney Barrett, of the Seventh Circuit Court of Appeals, to take Ginsburg’s place, women would be at serious risk of losing their constitutionally protected right to abortion. Judge Barrett would become the fifth woman appointed to the Supreme Court in its two-hundred-and-thirty-year history. The story of how the first female Justice, Sandra Day O’Connor, dealt with abortion law reveals much about why this issue is so difficult, and why we may be headed back to the age of proverbial back alleys.

In 1973, the U.S. Supreme Court ruled, 7–2, in the landmark case of Roe v. Wade, that women have a constitutional right to abortion. The decision, written by Justice Harry Blackmun, gave women an unfettered right to abortion in the first trimester of pregnancy, limited thereafter by the state’s interest in the mother’s health and in protecting a “viable” fetus that could live outside the womb. In an epic miscalculation of the mood of American politics, the majority of Justices seemed to believe that they were merely putting the court’s imprimatur on a social liberalization whose time had come. Almost immediately, a backlash erupted from the new Christian right. The Reverend Jerry Falwell claimed that he had an epiphany when he read news of the Roe v. Wade decision, on January 23, 1973. He instantly knew in his heart, he said, that evangelicals needed to organize into a vast pro-life movement to undo the Supreme Court’s decision. By 1980, Falwell’s organization, the Moral Majority, would try to make abortion a litmus test for millions of voters all over the country, particularly those voting in Republican primaries. Various G.O.P.-controlled state legislatures began passing laws seeking to outright overturn Roe, or to test how much they could limit women’s choice.

When, in 1981, Ronald Reagan nominated Sandra Day O’Connor to the Supreme Court, her views on abortion became a source of intense speculation. At her confirmation hearings, O’Connor, an Arizona appellate-court judge and a former Republican state senator, was folksy and disarming, if not entirely forthcoming, about her own views. She said she was opposed to abortion as a personal matter, as “birth control or otherwise,” but she added, “I’m over the hill. I am not going to be pregnant anymore, so it is perhaps easy for me.” (She was fifty-one and had undergone a hysterectomy three months earlier.) She was circumspect with everyone, including her family. It is almost certain that she never favored outlawing abortion altogether, but it is also likely that she struggled in her own mind to settle on the proper legal limits. In the coming years, when the Roe decision came under fire from conservative activists and the Supreme Court’s balance shifted toward the Republican Party, her struggle became the whole country’s.

The pro-life movement showed up at the Supreme Court on January 22, 1983, on the tenth anniversary of Roe v. Wade. Thousands of protesters thronged outside, in part because the Justices had agreed to take another abortion case, City of Akron v. Akron Center for Reproductive Health, Inc. In Ohio, the City of Akron implemented rules requiring women to sign “consent forms,” listen to a lecture from the doctor that a fetus is “human life from the moment of conception,” and return to the clinic after a twenty-four-hour waiting period before the abortion could be performed.

The Court voted on the Akron case in early December, and Justice O’Connor laid out her views in her personal notes. In her steady-handed script, she wrote, “There is simply no justification in Constitutional theory for having a different standard or test for the different trimesters. Seems it puts us in the business of being a science review board. The interest of the state in protecting the unborn is essentially the same at all stages of pregnancy. I would permit state regulations at every stage which do not unduly burden the right of the woman to terminate her pregnancy.”

O’Connor was moved less by constitutional theory than by the purely practical problems of judges trying to decide when a fetus was “viable,” or able to live outside the womb. Medical progress meant that “viability” would become earlier and earlier, which meant, as she later put it, that Blackmun’s trimester framework in Roe was “on a collision course with itself.” O’Connor was willing to let the states restrict abortions as long as they did not put an “undue burden” on the woman’s right to choose. The phrase “undue burden” had appeared in the Reagan Administration’s brief. It was a purposefully vague term, leaving plenty of room for the states and the courts to maneuver and litigate in the years to come. But, significantly, the Reagan Administration had not tried to overturn Roe completely. In June,1983, six Justices voted to knock down Akron’s restrictions, while three—O’Connor, William Rehnquist, and Byron White—voted to uphold them. Roe survived intact.

The crowds kept getting larger. On January 23, 1989, the sixteenth anniversary of Roe v. Wade, more than sixty thousand demonstrators assembled on the Mall to protest the famous decision. Over loudspeakers, the newly inaugurated President George H. W. Bush told them—and sent a not-so-subtle signal to the Supreme Court—that the time had come to overrule Roe. The political pressure of the anti-abortion movement had continued to mount: President Bush, once a Planned Parenthood–supporting moderate, had felt compelled to champion the right-to-life cause.

Two weeks earlier, the Court had agreed to rule in a case called Webster v. Reproductive Health Services, on a Missouri law sharply limiting abortion. Missouri legislators called it the “kitchen sink” law, because they had put in every restriction to abortion they could think of, from a preamble declaring that “life begins at conception” to prohibiting public hospitals from performing abortions that were not necessary to save the life of the mother. In O’Connor’s chambers, the mail stacked up—letters with photos of dead fetuses in one pile, letters with photos of coat hangers (symbol of back-alley abortions in the pre-Roe era) in another. “The Battle over Abortion,” was the cover line of Newsweek the week that the Webster case was argued before the Supreme Court, with a special focus on “Justice O’Connor’s Key Role.”

O’Connor’s understanding had deepened in the course of the past few years, as her eldest son, Scott, and his wife, Joanie, had tried to conceive. Finally, through a fertilization procedure, Joanie had become pregnant. On Mother’s Day, 1989, just over two weeks after the oral arguments in Webster, O’Connor joined her husband, son, and daughter-in-law to view an ultrasound video of her first grandchild. “We watched a terrific video of ‘Baby O’Connor’ at 4 ½ months since conception and about six inches long,” O’Connor’s husband, John, wrote in his diary that night. “I couldn’t help reflect that SOC was watching pictures of a fetus of her grandchild at a time when she was concurrently being viewed as the swing vote on the abortion issue.”

In the end, O’Connor went with an approach entirely consistent with her jurisprudence: to say as little as possible and to let the argument evolve through the delicate balance between legislatures elected by the people and judges sworn to protect the Constitution. She concluded that, properly read, the Missouri regulations did not impose “an undue burden” on a pregnant woman, her test from the Akron case, and that there was no need to revisit the constitutional validity of Roe v. Wade. In other words, the battle would return to the states, which could keep trying to restrict abortion—and keep trying to persuade the Court to throw out the embattled precedent.

In the winter of 1992, a hundred thousand people showed up at the annual right-to-life protest march on the Roe v. Wade anniversary. With the replacement of the liberal Thurgood Marshall by the conservative Clarence Thomas, it appeared likely that the Court would have five votes to overturn Roe. The state of Pennsylvania had enacted the most restrictive law yet: women wanting an abortion had to wait twenty-four hours after contacting a clinic to get one; they had to undergo a mandatory lecture on fetal development; and, if a woman was married, she had to notify her husband.