Retired Supreme Court Justice John Paul Stevens has died at the age of 99. Stevens was appointed to the court in 1975 by President Gerald Ford. Although a moderate Republican, Stevens led the liberal wing of the court for decades and is considered a hugely influential justice who authored key decisions on cases around presidential powers, national security and campaign financing, among other issues.

In his dissent in 2000’s Bush v. Gore, he wrote: “Although we may never know with complete certainty the identity of the winner of this year’s presidential election, the identity of the loser is clear. It is the nation’s confidence in the judge as impartial guardian of the rule of law.” At the height of President George W.Bush’s “war on terror,” he wrote the decision granting Guantánamo prisoners legal rights and access to federal courts. In his dissent for Citizens United v. Federal Election Commission, he wrote the decision “threatens to undermine the integrity of elected institutions across the nation.”

Stevens said at the end of his tenure on the court that his one regret was his 1976 vote upholding a Texas capital punishment statute that revived the death penalty. Stevens later opposed most death penalty sentences. He retired from the court in 2010 as the second-longest-standing justice.