Sandra Day O’Connor, the first woman to serve as a justice on the U.S. Supreme Court, has died.

O’Connor was 93 years old.

She died in Phoenix, Arizona, on Friday “of complications related to advanced dementia, probably Alzheimer’s, and a respiratory illness,” the Supreme Court said in a statement.

O’Connor was appointed to the court in 1981 by President Ronald Reagan and served nearly a quarter-century, retiring in 2006.

She was replaced by Justice Samuel Alito, who in 2022 wrote the majority opinion overturning a federal right to abortion that had been protected for decades by the cases Roe v. Wade and Planned Parenthood v. Casey.

O’Connor had co-authored the majority opinion in the latter case, which Alito blasted for having “enflamed debate and deepened division” in the United States.

She stepped back from public life in late 2018, after having problems with her short-term memory, her family said at the time.

Chief Justice John Roberts, in a statement released by the court, said, “A daughter of the American Southwest, Sandra Day O’Connor blazed an historic trail as our Nation’s first female Justice. She met that challenge with undaunted determination, indisputable ability, and engaging candor.”

“We at the Supreme Court mourn the loss of a beloved colleague, a fiercely independent defender of the rule of law, and an eloquent advocate for civics education,” Roberts said. “And we celebrate her enduring legacy as a true public servant and patriot.”

Georgetown University Law School Professor Julie O’Sullivan, who clerked for O’Connor in the mid-1980s, said she was a “brilliant” justice who came on to the court as a libertarian, but “who evolved quite a bit” over the years in terms of legal philosophy.

O’Sullivan also said that O’Connor was “a very courageous woman to take” on the role of the first female justice.

“She was always very conscious that everybody was watching,” said O’Sullivan, noting that O’Connor was known to say that “she didn’t mind being the first, but she didn’t want to be the last.”

While still most junior justice on the court, O’Connor insisted that the nine justices “all have lunch together” regularly, and strongly believed in getting along with her colleagues, regardless of their differences of opinion, O’Sullivan said.

And “she knew how to get to five,” O’Sullivan noted, referring to the minimum number of justices needed for a majority ruling in most cases. “She was very strategic.”

During her tenure, O’Connor was joined on the nine-member Supreme Court by the late Justice Ruth Bader Ginsburg, who was appointed by President Bill Clinton in 1993. Before O’Connor died, Ginsburg was the most recent justice to have died, in September 2020.

Four other women have been appointed to the court since Ginsburg was, all of whom are currently serving: Sonia Sotomayor, Elena Kagan, Amy Coney Barrett and Ketanji Brown Jackson.

O’Connor was serving as a judge on the Arizona Court of Appeals when Reagan, a Republican, tapped her to become the first female on the Supreme Court in its then 191-year history.

The El Paso, Texas, native previously served as assistant attorney general of Arizona, as a member of the Arizona state Senate, where she was majority leader at one point, and as a judge of the Maricopa County Superior Court.

O’Connor’s husband, John, died in 2009, three years after she retired to care for him when he was suffering from Alzheimer’s.

She is survived by three sons, six grandchildren and her brother.

The Supreme Court’s press office said funeral arrangements for O’Connor will be released when available.