GEOFF BENNETT: Retired Supreme Court Justice David Souter, who spent nearly 20 years on the nation's highest court, has died.

Chief Justice John Roberts praised Souter in a statement today, saying he served the court with great distinction and brought uncommon wisdom and kindness to a lifetime of public service.

Souter was a critical figure in several key battles in the court over issues like abortion and the 2000 presidential election.

William Brangham has this remembrance.

WILLIAM BRANGHAM: After ascending to the nation's highest court, Justice David Souter quickly turned from a great hope for conservatives into a judge who sided most frequently with the court's liberals.

And because of it, he inspired a Republican rally cry, no more Souter.

He grew up in a small New Hampshire town and carried that Yankee upbringing with him to Washington, according to a former law clerk, Noah Feldman.

NOAH FELDMAN, Former Justice Souter Law Clerk: He never wore a coat in Washington, D.C., because as a New Englander, he took the view that it was never cold enough to need a coat, and that included at the memorial service for Justice Harry Blackmun, when the justices had to stand outside for more than two hours in pelting snow, and he absolutely refused to wear a coat.

WILLIAM BRANGHAM: From Harvard Law, Souter became a prosecutor, and then his home state's attorney general.

President George H.W.

Bush appointed him to the federal bench, and then, just a few years later, tapped him to serve on the nation's highest court, when liberal Justice William Brennan stepped down.

GEORGE H.W.

BUSH, Former President of the United States: The Supreme Court must be guided by independent minds, and its members are appointed for life, largely to keep them above the flames of political passion.

WILLIAM BRANGHAM: Despite having little national profile, his fellow New Hampshirite Bush's Chief of Staff John Sununu assured conservative skeptics of his bona fides.

And Souter was confirmed 90-9, but he quickly angered some of his Republican backers.

In 1992's Planned Parenthood v. Casey, Souter joined the court's moderates to uphold abortion rights nationwide.

And in one notable dissent in the controversial 2000 election case Bush v. Gore, Souter argued Florida should continue its recount.

NOAH FELDMAN: The biggest mistake that people made about David Souter was thinking that somehow he was a conservative when he went on to the court and then magically became a liberal.

In fact, Justice Souter was hiding in plain sight the whole time.

He believed that the Constitution was not a dead document that should be interpreted according to what people thought 200-and-some years ago, but rather was a document that needed to be interpreted in the light of our changing needs and circumstances.

WILLIAM BRANGHAM: Months after President Obama took office, Souter announced his decision to retire and move back home to New Hampshire.

Justice Sonia Sotomayor took his place on the bench.

While Souter rarely spoke about politics after stepping down, in a 2012 interview with the "News Hour"'s Margaret Warner, he warned of the fragility of American democracy.

DAVID SOUTER, Former U.S. Supreme Court Associate Justice: I don't worry about our losing republican government in the United States because I'm afraid of a foreign invasion.

What I worry about is that, when problems are not addressed, people will not know who is responsible.

And when the problems get bad enough, as they might do, for example, with another serious terrorist attack, as they might do with another financial meltdown, someone person will come forward and say, give me total power and I will solve this problem.

NOAH FELDMAN: Justice Souter's whole career was devoted to being an example of the rule of law and a justice of the Supreme Court who was completely uninterested in partisanship or political ideology, but was just committed to the idea of getting the law right.

And in the current moment, when the threat to the rule of law is unprecedented, we need that model.

WILLIAM BRANGHAM: Former Supreme Court Justice David Souter was 85 years old.

For the "PBS News Hour," I'm William Brangham.