One of the heros of American conservatism has died, after a long battle with thyroid cancer. Supreme Court Chief Justice William Rehnquist has died at home at the age of 80, and the tributes have been pouring in.His death means the Court needs a new boss, and a new member, giving President Bush another opportunity to make a key political appointment that could deeply affect the course of the nation for years to come. Rehnquist has already left his stamp on an era. He was first appointed by Richard Nixon in 1971, and Ronald Reagan gave him the top job in American justice 15 years later. He boosted state over federal rights, cut appeals by death row prisoners, and made public funds available to religious groups, but he was not able to reduce abortion and gay rights, nor maintain the death penalty for minors.