John Paul Stevens, a moderate midwestern Republican and former antitrust lawyer from Chicago who evolved into a savvy and sometimes passionate leader of the Supreme Court's liberal wing and became the third-longest-serving justice on the high court before his retirement in 2010, died July 16 at a hospital in Fort Lauderdale, Fla. He was 99.

The cause was complications from a stroke that he suffered yesterday, according to an announcement from the Supreme Court. The only justices who served longer were William O. Douglas, whom Justice Stevens replaced in 1975, and Stephen J. Field, a nominee of President Abraham Lincoln who served for much of the late 19th century.

During his 35-year tenure, Justice Stevens left his stamp on nearly every area of the law, writing the court's opinions in landmark cases on government regulation, the death penalty, criminal law, intellectual property and civil liberties.

Justice Stevens also spoke for the court when it held presidents accountable under the law, writing the 1997 decision that required President Bill Clinton to face Paula Jones's sexual harassment suit, and the 2006 opinion that barred President George W. Bush from holding military trials for prisoners at the Guantanamo Bay Naval Base without congressional authorization.

But it was in his frequent dissenting opinions that Stevens set forth a view of the law that seemed increasingly -- but not automatically -- liberal as the years went by and as the court itself shifted right.

A strong proponent of federal power, Justice Stevens sharply criticized the limitations Chief Justice William H. Rehnquist and his fellow conservatives put on Congress's power to define and remedy violations of federal law by the states.

In Bush v. Gore, the 2000 election case that helped George W. Bush win the presidency, Justice Stevens lamented in dissent that the five Republican justices who backed Bush would "lend credence to the most cynical appraisal of the work of judges throughout the land."

In 2004, when the court, citing technical reasons, dismissed the plea of U.S. citizen Jose Padilla, who was being held incomunicado as an enemy combatant, Stevens blasted the majority for ducking issues "of profound importance."

"If this Nation is to remain true to the ideals symbolized by its flag, it must not wield the tools of tyrants even to resist an assault by the forces of tyranny," he wrote.

Justice Stevens's reference to the flag harked back to the 1989 dissent in which the decorated Navy veteran of World War II joined Rehnquist and other conservatives in dissenting from a ruling that recognized a First Amendment right to burn the American flag.

"The ideas of liberty and equality have been an irresistible force in motivating leaders like Patrick Henry, Susan B. Anthony, and Abraham Lincoln, schoolteachers like Nathan Hale and Booker T. Washington, the Philippine Scouts who fought at Bataan, and the soldiers who scaled the bluff at Omaha Beach," Justice Stevens wrote in that case. "If those ideas are worth fighting for -- and our history demonstrates that they are -- it cannot be true that the flag that uniquely symbolizes their power is not itself worthy of protection from unnecessary desecration."

This article was written by Charles Lane, a reporter for The Washington Post.