associate justice of the Supreme Court of the United States from 1994.

Breyer received bachelor's degrees from Stanford University (1959) and the University of Oxford (1961), which he attended on a Rhodes scholarship, and a law degree from Harvard University (1964). In 1964–65 he clerked for U.S. Supreme Court Justice Arthur J. Goldberg (Goldberg, Arthur J.). He taught law at Harvard University from 1967 to 1994.

Breyer took leave from Harvard in 1973 to serve as an assistant prosecutor in the Watergate (Watergate Scandal) investigation. In 1974–75 he was special counsel to the U.S. Senate Judiciary Committee, and from 1979 to 1981 he was its chief counsel, working on projects ranging from the federal criminal code to airline and trucking deregulation. In 1980 he was appointed by President Jimmy Carter (Carter, Jimmy) to the United States Court of Appeals for the First Circuit, becoming its chief judge in 1990. In 1994 President Bill Clinton (Clinton, Bill) nominated Breyer to fill the seat of the retiring justice Harry Blackmun (Blackmun, Harry A.). As a pragmatic moderate acceptable to Democrats and Republicans alike, Breyer was easily confirmed by the Senate (87–9).

More liberal than most other members of the court, Breyer was highly regarded, even by conservatives, for his analytic rather than ideological approach to the Constitution. In the area of civil rights, Breyer consistently sided with efforts to dismantle historical and symbolic vestiges of racial segregation (segregation, racial). In Bush (Bush v. Gore) v. Gore (2000; see United States: The Bill Clinton administration (United States)), which settled that year's controversial presidential election between George W. Bush (Bush, George W.) and Al Gore (Gore, Al), he issued a passionate yet precise dissent. He argued that, by failing to refuse the case under the rubric of the political-question doctrine (which the court often had invoked in order to sidestep controversial issues that it thought were best handled by the legislature) and by deciding the case on the basis of equal protection (i.e., it ruled that manual recounts of certain votes in Florida violated the rights of voters whose ballots were not manually reviewed), the court had undermined its integrity and authority. In McConnell v. Federal Election Commission (2003), he joined a majority in holding that limits on campaign advertisements and contributions imposed by the Bipartisan Campaign Reform Act of 2002, popularly known as the McCain-Feingold Act, did not violate the First Amendment's guarantee of freedom of speech.

Breyer is the author of Breaking the Vicious Circle: Toward Effective Risk Regulation (1993), an analysis of government environmental and health regulations, and Active Liberty: Interpreting Our Democratic Constitution (2005), an outline of his judicial philosophy.