When President Ronald Reagan named Sandra Day O’Connor in 1981 to be the first woman on the Supreme Court, replacing Potter Stewart, she was known as a traditional conservative in her adopted home state of Arizona and was championed for the job by that state’s Republican Sen. Barry Goldwater. As the court moved to the right over the past two decades, O’Connor was seen more as a moderate influence, and she often provided the deciding vote in 5-4 majorities, straddling the line between the conservative and liberal wings on the bench.

During 24 terms on the court, O’Connor has consistently shown sensitivity to public opinion and political conditions, and a preference for narrow, one-step-at-a-time judicial decision-making. But since the last court vacancy, in 1994, she more than any other justice has been responsible for unraveling Chief Justice William H. Rehnquist’s conservative majorities.

In 1992, she joined with Justices Anthony M. Kennedy and David H. Souter in writing the majority opinion in a 5-4 decision that, in essence, upheld the constitutional right to abortion.

More recently, she joined with liberal Justice John Paul Stevens in upholding the McCain- Feingold campaign finance law and fashioned the main opinion requiring some form of courtlike hearings for U.S. citizens held as enemy combatants in the war on terror.

In 2003, she made her first vote to uphold a racial preference, in a 5-4 decision backing the affirmative-action policies of the University of Michigan