Now in what may be the twilight of his service -- Stevens has hired only one clerk so far, the normal allotment for a retired justice -- a look back at his tenure shows how central he was to many of the court's greatest cases.
Various analyses of Supreme Court voting place him either in the center of the court's jurisprudence or firmly in the liberal wing, all based on the same cases.
Stevens joined the Supreme Court in 1975, taking the oath two days after being unanimously confirmed by the U.S. Senate.
His Library of Congress biography says new justices on the court are usually seen but little heard, typically joining majorities or dissents but seldom writing themselves. However, in his first term on the court, Stevens wrote 17 separate majority concurrences, agreeing with the judgment of the majority but disagreeing on some of the details, and 27 separate dissents -- far more opinions than any other justice that term.
Over the last three and a half decades, Stevens has made himself felt on the major issues before the court. And his quiet questions from the bench uncharacteristically cause the other members -- who sometimes like to interrupt -- to shut up and listen.
Stevens helped restore the death penalty in 1976, one of three authors of the majority opinion declaring it constitutional, but has come to question its effectiveness and constitutionality in recent years.
On abortion, 1992's Planned Parenthood vs. Casey found a broken majority of five justices upholding Roe vs. Wade, 1973's recognition of a woman's right to an abortion. But the majority was comprised of several pluralities, and Stevens wrote his own opinion concurring in the judgment but objecting to its restrictions on when an abortion should be allowed.
"My disagreement with the joint opinion begins with its understanding of the trimester framework established in Roe," Stevens wrote. "Contrary to the suggestion of the joint opinion … it is not a 'contradiction' to recognize that the state may have a legitimate interest in potential human life and, at the same time, to conclude that that interest does not justify the regulation of abortion before viability (although other interests, such as maternal health, may). The fact that the state's interest is legitimate does not tell us when, if ever, that interest outweighs the pregnant woman's interest in personal liberty."
Stevens joined the majority in 2000's Stenberg vs. Carhart striking down Nebraska's ban on "partial-birth abortion." But he wrote separately to cast scorn on the central idea of the Nebraska law, that there is a significant difference between "dilation and evacuation," which involves dilation of the cervix, removal of at least some fetal tissue -- which Nebraska allowed -- and the method which the state tried to partly ban, a variation of D&E, known as "intact D&E," used after 16 weeks.
"Intact D&E" involves removing the fetus from the uterus through the cervix "intact," in one pass rather than several passes, including the feet-first method is known as "dilation and extraction" (D&X), ordinarily called "partial birth abortion."
"Although much ink is spilled today describing the gruesome nature of late-term abortion procedures," Stevens wrote, "that rhetoric does not provide me a reason to believe that the procedure Nebraska here claims it seeks to ban is more brutal, more gruesome, or less respectful of 'potential life' than the equally gruesome procedure Nebraska claims it still allows. ... The rhetoric is almost, but not quite, loud enough to obscure the quiet fact that during the past 27 years, the central holding of Roe v. Wade ... has been endorsed by all but four of the 17 Justices who have addressed the issue. That holding -- that the word 'liberty' in the 14th Amendment includes a woman's right to make this difficult and extremely personal decision -- makes it impossible for me to understand how a state has any legitimate interest in requiring a doctor to follow any procedure other than the one that he or she reasonably believes will best protect the woman in her exercise of this constitutional liberty."
Stevens also joined the four-member dissent in the 2007 case that upheld the 2003 federal ban on "partial-birth abortions."
On affirmative action, Stevens has moved from right to left over the years.
In 1978's University of California Regents vs. Bakke, Stevens wrote a concurrence supporting the plurality opinion that struck down the university system's policy that prevented a qualified candidate's admission because he was white.
But in 2003's Grutter vs. Bollinger, Stevens joined the 5-4 majority upholding the affirmative action policy of the University of Michigan's Law School admissions program. The majority opinion written by Justice Sandra Day O'Connor said the policy was "narrowly tailored" to achieve the goal of a diverse student body and did not violate the equal protection provisions of the 14th Amendment.
At times Stevens seemed very conservative -- or at least conservative on a suspect's rights.
He wrote the 6-3 majority opinion in 1982's United States vs. Ross in which he said police may search compartments and containers in a stopped vehicle, even those not in "plain view," when there is "probable cause to do so" -- the same standard needed to obtain a search warrant from a judge. Stevens took the judge out of the equation.
On prayer in public schools, Stevens wrote the 6-3 opinion in 1985's Wallace vs. Jaffree that said a state-required "moment of silence" at the beginning of the school day was unconstitutional. The decision struck down an Alabama "moment of silence" law.
In 1992's Cipollone vs. Liggett, Stevens wrote the 7-2 opinion that said cigarette makers who lie about the dangers of smoking or otherwise misrepresent their products can be sued under state law -- opening the door to a flood of suits in smoking-related deaths.
Stevens wrote the unanimous opinion in 1997's Clinton vs. Jones, ruling that Paula Jones' sexual harassment suit against President Clinton could continue.
Stevens said the courts were not required to delay the suit until Clinton left office in 2001, and the lawsuit would not be disruptive. Stevens turned out to be a poor prophet. Clinton's testimony during the suit about his relationship with Monica Lewinsky led to his eventual impeachment by the House and acquittal by the Senate.
Stevens also wrote the unanimous opinion in 1984's Chevron USA vs. Natural Resources Defense Council, universally recognized as the most cited decision in Supreme Court history.
Writing for a 6-0 court -- three justices recused themselves, presumably because of conflicts of interest -- Stevens said, "When a challenge to an agency construction of a statutory provision, fairly conceptualized, really centers on the wisdom of the agency's policy, rather than whether it is a reasonable choice within a gap left open by Congress, the challenge must fail. In such a case, federal judges -- who have no constituency -- have a duty to respect legitimate policy choices made by those who do. The responsibilities for assessing the wisdom of such policy choices and resolving the struggle between competing views of the public interest are not judicial ones."
In other words, when Congress is vague in a law, U.S. agencies can broadly interpret it. "Chevron deference" was born.