Two months after publishing his 531-page memoir, retired Supreme Court Justice John Paul Stevens passed away Tuesday at the age of 99.

Justice Stevens’ life spans nearly half of American history. He was at the Democratic National Convention in 1932 when FDR proposed the New Deal, and he wrote the Supreme Court opinion in 1997 that denied President Bill Clinton immunity in a sexual harassment suit brought by Paula Jones.

And he was extraordinarily active right up until the end of his life, weighing in on Justice Brett Kavanaugh (disqualified due to his behavior at his confirmation hearings), gun control (D.C. v. Heller was “the most clearly incorrect decision that the Supreme Court announced during my tenure on the bench”), and six amendments he’d like to see added to the Constitution.

Appointed in 1975 by President Gerald Ford and confirmed by a vote of 98-0, Justice Stevens went on to become the third longest-serving Supreme Court justice in history, retiring in 2010.

Famously, Justice Stevens became known as one of the court’s most liberal members, despite being appointed by a Republican president. His strong dissents in Bush v. Gore, Citizens United, and D.C. v. Heller cemented that reputation. So did his gradual evolution on the death penalty; though he joined the court in holding capital punishment constitutional in 1976, he restricted it in 2002 and by 2008, he had come to the view that it violated the Eighth Amendment’s ban on “cruel and unusual punishment.”

In Bush v. Gore, for example, Justice Stevens wrote, perhaps prophetically, that the court’s decision

can only lend credence to the most cynical appraisal of the work of judges throughout the land... 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 perfectly clear. It is the Nation's confidence in the judge as an impartial guardian of the rule of law.

And, in his post-court writing, Justice Stevens has promoted ideas beloved of liberals: campaign finance regulation, gun control, abolishing the death penalty, and, more recently, partisan gerrymandering, which the Supreme Court held last month to be constitutional, but which Justice Stevens said is a violation of the constitution’s guarantee of Equal Protection under the laws. In 2008, Stevens declined to answer whether he was still a Republican.

But, rather like Chief Justice John Roberts, Justice Stevens might be better understood according to jurisprudence than politics. Chief Justice Roberts is often ideologically conservative where Justice Stevens was not. But both have held to a relatively conservative judicial philosophy, even when it placed them on surprising sides of various controversies.

In a 2005 speech, Justice Stevens noted that he had, several times, voted differently as a justice than he would have as a legislator, even calling some of the laws he had affirmed “unwise.”

Of course, all judges say they are interpreting the law and not making it. But Justice Stevens’ remarkable evolution from Republican appointee to liberal firebrand—much more than his colleague Justice Kennedy’s evolution from conservative to centrist—can also be understood in terms of judicial minimalism, respect for precedent, and other priorities Justice Stevens shared with the current chief justice.

After all, Justice Stevens’ strongest dissents weren’t simply in controversial cases, they were in cases where the court’s conservative majority boldly created new holdings in defiance of precedent and history: a Second Amendment right to own personal firearms (as Justice Stevens noted, several state laws that existed at the time of the amendment’s passage would be unconstitutional under D.C. v. Heller); the Supreme Court interpreting state constitutional provisions (in Bush v. Gore, and in defiance of all relevant precedent on the subject); and the adoption, in Citizens United, of the views that money is the same as speech, that corporations are the same as people, and thus that corporate political spending cannot be regulated.

These weren’t simply right-wing positions, they were whole new judicial territories where previously judges had feared to tread. One could read Justice Stevens as a liberal in these cases or as a judicial conservative with a more restrained view of the role of a judge.

One can discern similar, though more conservative, currents within the opinions of Chief Justice Roberts, who in the last term voted to uphold a key doctrine regarding respect for administrative agency decisions, contrary to the expectations of conservatives (as it happens, Justice Stevens authored the Chevron case that articulated the most important form of this deference) and called the Trump administration’s bluff on its shifting explanations for asking about citizenship on the census.

“ Justice Stevens’ fundamentally conservative understanding of what a judge does led him to liberal results despite coming from a centrist Republican background. ”

Nor is this a recent phenomenon. Last term, Chief Justice Roberts sided with the court’s liberals on digital privacy. And, of course, he has twice (thus far) upheld the Affordable Care Act, which conservatives would dearly like to strike down.

In all of these cases, Chief Justice Roberts’ judicial conservatism trumped his ideological conservatism. (In other cases, particularly on voting rights, the opposite has happened.) Just as Justice Stevens’ fundamentally conservative understanding of what a judge does—in contrast, say, with freewheeling ideological firebrands like the late Justice Antonin Scalia or Justice Clarence Thomas—led him to liberal results despite coming from a centrist Republican background.

No doubt, Justice Stevens will be remembered as a liberal hero. Certainly he gave progressives much to cheer about, or, in his last decade on the court, much to console themselves with.

But in both his judicial philosophy and his personal demeanor—the ever-bow-tied, white-haired justice seems universally regarded with fondness by his former clerks and colleagues, and was known for politely prefacing questions from the bench with “May I just ask this question”—Justice Stevens may hark back to a less politicized time in our country, when politeness rather than profanity was the order of the day, and when the law still protected the weak from the strong.