-- The Supreme Court is split on several key areas of the law. Among the issues on which the change of a single justice could tip the balance:
•Abortion rights. Five of the nine justices — Anthony Kennedy and liberals John Paul Stevens, David Souter, Ruth Bader Ginsburg and Stephen Breyer — have endorsed the 1973 Roe v. Wade ruling that legalized abortion nationwide.
In 2007, a separate five-justice majority — Kennedy and conservatives John Roberts, Antonin Scalia, Clarence Thomas and Samuel Alito — ruled for the first time that government may ban a particular abortion procedure, in that case a method critics call "partial birth" abortion. The decision reversed a 2000 ruling that said a ban on the procedure was unconstitutional without an exception to protect a woman's health.
•Race-based policies. In 2007, the court struck down programs in Louisville and Seattle that tried to make schools more racially diverse by using students' race as a factor in determining where they could enroll. Roberts, Scalia, Kennedy, Thomas and Alito voted in the majority; Stevens, Souter, Ginsburg and Breyer dissented. In 2003, the court, led by the liberals and then-justice Sandra Day O'Connor, allowed race-based decisions in higher education admissions.
•Terrorism A narrow majority has ruled against the Bush administration's attempts to keep federal judges from reviewing the cases of detainees held at Guantanamo Bay, Cuba.
Last June, the court held that foreign detainees at the U.S. naval base have a right to challenge their cases in federal court. Kennedy joined liberals Stevens, Souter, Ginsburg and Breyer in the majority.
By Joan Biskupic