Sandra Day O’Connor, the first woman to sit on the US Supreme Court, died Friday. According to an announcement from the court, O’Connor died of “complications related to advanced dementia, probably Alzheimer’s, and a respiratory illness” at the age of 93.

O’Connor was appointed to the court in 1981 by then-president Ronald Reagan. During her more than 24 years on the court, she authored numerous landmark opinions including Grutter v. Bollinger, which allowed race to be considered in college admissions, and Hamdi v. Rumsfeld, which allowed the government to detain enemy combatants but also gave the detainees certain due process rights. O’Connor was part of the per curiam opinion in the 2000 Bush v. Gore election case, and was one of three co-authors of the opinion in the seminal abortion rights case Planned Parenthood v. Casey.

O’Connor retired in 2006 but remained active in public life for many years. In 2009 O’Connor and the Institute for the Advancement of the American Legal System began a campaign to urge state legislatures to move towards merit-based judicial appointments instead of direct judicial elections. O’Connor also founded iCivics, a civics education platform.