Mississippi University for Women v. Hogan:
In 1982, in a 5-4 decision, O'Connor wrote the majority opinion on gender stereotypes. The case involved reverse discrimination, of a man who was excluded from a state-operated nursing school, but O'Connor's opinion dashed outdated notions of defined and stereotypical roles for men and women, unrelated to their actual abilities.
Meritor Savings Bank v. Vinson:
In 1986, O'Connor joined the rest of the justices in an unanimous opinion declaring that sexual harassment can create a hostile work environment and is a form of sex discrimination under federal law. An employee subjected to the discrimination could sue her employer, the court said, and a grievance procedure and policy alone were not protection from liability.
Planned Parenthood of Southeastern Pennsylvania v. Casey:
In a 1992 abortion decision, with several opinions by groupings of justices, O'Connor provided a "middle ground" consensus opinion. The case revisited Roe v. Wade, which said that states could not make abortion illegal in the first trimester or whenever a woman's life or health were endangered. Casey did not overturn Roe, but said states could restrict abortion in all trimesters, so long as the restrictions did not impose an "undue burden" on a woman's right to choose and protected her life and health. The court explicitly permitted states to pass laws requiring women to read state-scripted literature and to impose a waiting period before a woman could obtain an abortion, but rejected a requirement that a woman must notify her husband about an abortion.
United States v. Virginia:
In 1996, O'Connor signed on to an opinion written by the other woman justice, Ruth Bader Ginsburg, and signed by five other justices, in holding that the Virginia Military Institute's male-only policy violated the equal protection clause of the U.S. Constitution.
Davis v. Monroe County Board of Education:
In 1999, O'Connor wrote the majority opinion in a 5-4 ruling holding that a claim may be brought under Title IX to challenge the sexual harassment by one student of another where the school authorities have failed to act.
Stenberg v. Carhart:
In a 2000 case challenging a ban on abortion practices in Nebraska, O'Connor provided the swing vote holding that the law was unconstitutional because it was vaguely worded and could make doctors subject to arrest for performing abortions after the 12th week of pregnancy, and because it did not sufficiently protect women's health by providing an exception in the ban.
Grutter v. Bollinger:
In this 2003 case, O'Connor wrote the majority opinion in a 5-4 ruling upholding the use of affirmative action to promote diversity in university admission policies. The case supports affirmative action based on sex, as well as on race, according to the National Women's Law Center, an advocacy group in Washington, D.C.
Jackson v. Birmingham Board of Education:
In 2005, O'Connor was a deciding vote and wrote the majority opinion that said a school could not retaliate against an employee who complained of sex discrimination under Title IX. The case involved the coach of a girls' basketball team, a man, who was taken off the job when he complained that the female athletes were treated unfairly.
In some cases, O'Conner's moderate views were not enough to tip an opinion.
Nguyen v. INS:
In 2000, O'Connor was part of the four-justice dissent in a case of a child's status under immigration law. The majority held that the law was constitutional, even though it stated that a child was a citizen if his mother were a citizen, but not if his father were a citizen. The court held that this sex-based classification was okay.
In other cases, O'Connor's opinions swayed to the conservative side.
Webster v. Reproductive Health Services:
In 1989, O'Connor ruled with the 5-4 majority that upheld an anti-abortion law in Missouri. The law prohibited the use of public hospitals or facilities for abortions except where necessary to save a woman's life. She disagreed with three justices who wanted to take the opportunity to overturn the 1973 case of Roe v. Wade, which said that states could not make abortion illegal in all circumstances.
United States v. Morrison:
In 2000, O'Connor was the swing vote, but in this case she joined conservatives on the court in rejecting the federal Violence Against Women Act (VAWA), saying that Congress had exceeded its authority. In that case, a woman student at a Virginia college who was repeatedly raped sought civil relief under a federal civil rights law. The court said that there was not sufficient evidence that gender-motivated violence was a fit subject for federal law.
Bush v. Gore:
In 2000, in a 5-4 decision, O'Connor voted against Democrats who challenged the legality of the vote in Florida, essentially assuring George W. Bush his inauguration as President.
--Cynthia L. Cooper with research assistance from the National Women's Law Center and Women's eNews intern Kamelia Angelova.