Key dates in William H. Rehnquist's tenure on the U.S. Supreme Court:

—Jan. 7, 1972: Takes seat on Supreme Court after nomination by President Nixon (search). Confirmed by Senate, 68-26.

—Jan. 22, 1973: One of two dissenters in Roe v. Wade (search), which overturned individual states' laws against abortion and recognized the practice as a constitutional right.

—December 1981: Hospitalized for a week for withdrawal from a prescription drug he was taking for back pain.

—Sept. 26, 1986: Sworn in as chief justice after President Reagan names him to replace retiring Warren Burger (search); confirmed by Senate in 65-33 vote.

—June 29, 1988: Writes majority opinion upholding Independent Counsel Act (search), which was passed in post-Watergate era to help prevent abuses in the executive branch.

—April 26, 1995: Writes majority opinion striking down a federal law mandating a "gun-free zone" around public schools, in a landmark decision preserving states' rights.

—January 1999: Presides over President Clinton's impeachment trial in the Senate that eventually acquits him. Rehnquist's court had ruled in May 1997 that Paula Jones could sue Clinton for sexual harassment.

—Dec. 12, 2000: Joins four other Republican-nominated justices in Bush v. Gore ruling that stops presidential ballot recounts in Florida, making Republican George W. Bush the winner.

—June 27, 2002: Writes majority opinion declaring that an Ohio taxpayer-funded voucher program was not a violation of the separation of church and state; 96 percent of the students using vouchers in that case attended religious schools.

—Oct. 1, 2004: Turns 80 to become the second-oldest chief justice. Only Roger Taney, who presided in the mid-1800s until his death at 87, served longer.

—Oct. 25, 2004: Discloses he has thyroid cancer, prompting speculation about an imminent retirement one week before the presidential election.

—Jan. 20, 2005: — Emerges from months of seclusion to swear in President Bush.

—March 21, 2005: Defying expectations, returns to bench after five-month absence.