On October 3, 2005, Harriet Miers was nominated for Associate Justice of the U.S. Supreme Court by President George W. Bush to replace retired Associate Justice Sandra Day O'Connor. Miers was, at the time, White House Counsel, and had previously served in several roles both during Bush's tenure as Governor of Texas and President.

Sandra Day O'Connor was an American attorney, politician, and jurist who served as an associate justice of the Supreme Court of the United States from 1981 to 2006. O'Connor was the first woman to serve as a U.S. Supreme Court justice. She was a moderate conservative. Nominated by President Ronald Reagan, she was considered a swing vote for the Rehnquist Court and the first four months of the Roberts Court. Before O'Connor's tenure on the Court, she was an Arizona state judge and earlier an elected legislator in Arizona, serving as the first female majority leader of a state senate as the Republican leader in the Arizona Senate. Upon her nomination to the Court, O'Connor was confirmed unanimously by the United States Senate.