In the Supreme Court's blockbuster ruling that struck down a Texas law banning sodomy between homosexuals by a 6-to-3 vote, a majority of five justices sweepingly affirmed the Constitution's guarantee of a right to privacy. They overturned and apologized for a 17-year-old precedent. Writing for the court in Lawrence v. Texas, Justice Anthony M. Kennedy said that a state can't "demean" the existence of gay men and women or "control their destiny by making their private sexual conduct a crime."

The ruling and the opinion are remarkable, but it is Justice Antonin Scalia's biting, sarcastic dissent that has drawn keen attention. Even for an impassioned disagreement, his tone seems to breach the bounds of decorum.

Yet it would be a mistake to dismiss Scalia's views in the sodomy case (or any other) as the grumblings of a sore loser. His approach is simply a mutation in a long, sometimes surprising tradition. In the history of the court, "I dissent" are two of the most important words a justice can utter.

In the Lawrence case, Scalia fearlessly dishes out anger and accusation while making some scary predictions. Writing for himself, and for Chief Justice William Rehnquist and Justice Clarence Thomas, Scalia charges that the majority "has largely signed on to the so-called homosexual agenda" and "taken sides in the culture war." The ruling, he warns, entails "a massive disruption of the current social order." It effectively calls for "the end of all morals legislation" against "bigamy, same-sex marriage, adult incest, prostitution, masturbation, adultery, fornication, bestiality, and obscenity," he writes.

But Scalia wields his harshest language against an 11-year-old landmark ruling from which he already (famously) dissented. In Planned Parenthood v. Casey, the court upheld the right to abortion in part because overturning Roe v. Wade would "subvert the Court's legitimacy" by surrendering an established precedent to "political pressure." Scalia declared then that he was "appalled by" the reasoning. In this term's sodomy case, the justice mocks what he calls "the famed sweet-mystery-of-life passage" in the Casey holding ("At the heart of liberty is the right to define one's concept of existence, of the universe, and of the mystery of human life") as "the passage that ate the rule of law."

Scalia's derision speaks to the heart of his views. In the Casey ruling, he notes, the majority stressed stability and precedent. "To tell the truth," Scalia writes in Lawrence, "it does not surprise me, and should surprise no one" that by spurning stability and striking down precedent in Lawrence, the court has revealed its own yawning hypocrisy and "exposed Casey's extraordinary deference to precedent for the result-oriented expedient that it is." In an added dig at what he regards as the court's spineless flip-flop, Scalia flaunts his own consistency. He treats his Casey dissent as a precedent for his most recent one.

In addition to being condescending and sometimes mean, Scalia's Lawrence dissent is unmistakably antagonistic. It's written with contempt for what Scalia views as the logical contradictions and legal fallacies of the Kennedy opinion. It's hard not to see it as personal: Kennedy, the object of his scorn in the Texas case, was also a co-author -- with Justices Sandra Day O'Connor and David Souter -- of the Casey opinion.

Scalia is considered an intellectual leader of the court he has served on since 1986, but his stance as a dissenter seems anti-institutional and self-defeating. How could he persuade Kennedy or other justices to adopt his point of view in a subsequent case? With judicial temperament a bipartisan standard for judging judges, how could he burst into tantrums so injudiciously? And what about the impact on the Supreme Court: Don't his dissents undermine its authority? Isn't it time for him to bite his tongue?

The history of the dissenting justice goes back to the appointment of John Marshall as chief justice 202 years ago. Marshall was determined to elevate the status of a young, disrespected court. The court then followed a British practice, with justices resolving cases by announcing separate opinions one after another. According to Meredith Kolsky, writing in the Georgetown Law Journal, Marshall discarded the practice in favor of "announcing the judgment of the Court in a single opinion." The change presented the court "as a strong, unified body" and let the institution's voice reflect Marshall's outlook. Three years later, however, a justice named William Johnson (egged on by Thomas Jefferson, who appointed him) resisted what he described in a letter to Jefferson as "Lectures on the Indecency of Judges cutting at each other." Johnson asserted his independence and became the first dissenter.

During the first third of the 20th century, Justice Oliver Wendell Holmes earned a reputation as the great dissenter. In fact, he wrote relatively few dissents. But in 1905, he penned one of the best known in American law. In Lochner v. New York, a majority of five justices struck down a state regulation limiting the hours someone could work in a bakery. Until Lochner was overturned 32 years later, it gave the court the authority to nullify child labor laws, minimum wage laws and other reforms of social and economic conditions. The majority applied laissez-faire economics to make policy instead of interpreting law, engaging in a form of judicial activism against which every later version has been measured. Holmes's dissent began in a hush: "I regret sincerely that I am unable to agree with the judgment in this case and that I think it my duty to express my dissent."

Before 1925, many cases that rose to the high court were straightforward and produced unanimous decisions. When they didn't, the justices developed no steady habit of publishing dissent -- and sometimes their statements made in dissent were foolish, as when Justice James McReynolds predicted "an end to liberty" in the wake of a court ruling that said a milk control board in New York could set retail prices. But 1941 marked a turning point after Harlan Fiske Stone became chief justice. The previous chief, Charles Evans Hughes, could be elegiac on the topic ("A dissent in a court of last resort is an appeal to the brooding spirit of the law"), yet he favored unanimity and discouraged dissent. In contrast, Stone tolerated it. Under him, the rate of published dissents tripled. Since World War II, according to political scientist Lawrence Baum, the rates of dissent "have remained consistently far above the level" experienced before then. "It is clear," Baum wrote, "that the court's norms concerning dissent have changed fundamentally."

The vitality of a dissent, it's now widely agreed, springs from a justice being liberated to see the law his or her own way. At the Supreme Court Historical Society, Scalia explained in a lecture: "To be able to write an opinion for oneself, without the need to accommodate, to any degree whatever, the more-or-less-differing views of one's colleagues; to address precisely the points of law that one considers important and no others; to express precisely the degree of quibble or foreboding, or disbelief, or indignation that one believes the majority's disposition should engender -- that is indeed an unparalleled pleasure."

"Why Societies Need Dissent," a forthcoming book by the University of Chicago's Cass Sunstein, makes the case that "well-functioning societies take steps to discourage conformity and to promote dissent." The Supreme Court is animated by the same sort of deliberation that propels American society. "It is usual to think that those who conform are serving the general interest and that dissenters are antisocial, even selfish," Sunstein contends. "But in an important respect, the usual thought has things backwards. Much of the time, it is in the individual's interest to follow the crowd, but in the social interest for the individual to say and do what he thinks best."

In Bowers v. Hardwick, the 1986 Georgia case whose holding the court just overturned in the Texas sodomy case, Justice John Paul Stevens said what he thought best in a dissent. To the majority in the Texas case and to American law, Stevens's dissent is the one that matters in this area of the law. It set out the reasoning on which the current majority relied. Throughout their respective careers, Stevens has dissented more than twice as often as Scalia -- in 17.3 percent versus 7.9 percent of the cases each has sat on. Stevens has had plenty of opportunity to differ from the majority: Twenty-eight years ago, when centrist President Gerald Ford elevated Stevens from the federal appeals court to the high court, Stevens was seen as a moderate, if maverick, conservative. With the Rehnquist court's march to the right, the 83-year-old justice has become a moderate liberal.

The migration of Stevens's opinion about sodomy from minority to majority status fits a prophetic tradition of dissents. John Marshall Harlan's dissent from the majority's endorsement of racial segregation in the 1896 case Plessy v. Ferguson exemplifies the tradition. Fifty-eight years later, Harlan's opinion became the unanimous view of the court in Brown v. Board of Education. Louis D. Brandeis's dissent in the 1928 case Olmstead v. United States followed the same course. Disputing the court's ruling upholding the use of evidence obtained in an illegal wiretap, Brandeis argued that the Constitution protects a general right to privacy. In 1967, that became the majority view. The concept of privacy that Brandeis introduced was embraced by Stevens in his 1986 dissent about sodomy -- and by the majorities in the Casey and the Lawrence rulings.

Scalia's dissents may be too sharp and his arguments too impassioned. The court is likely to dismiss some of the reasoning he prizes and, as in his Texas dissent, write it off as hyperbolic rather than prophetic. (In another case, his colleague Souter observed: "Justice Scalia's dissent is certainly the work of a gladiator, but he thrusts at lions of his own imagining.") And Scalia's slashing style is likely to cost him in other ways: How could he expect to replace Rehnquist as chief justice, as was regularly forecasted this year by court-watchers handicapping the odds of retirements by sitting justices, if he is seen as a bully? But if his dissents are stretching the bounds of an American tradition, they also help us grasp why that tradition is essential.

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Lincoln Caplan, the author of "The Tenth Justice: The Solicitor General and the Rule of Law" (Knopf), is the Knight Senior Journalist at Yale Law School and the editor of Legal Affairs magazine.

The high court's ruling on sodomy prompted protesters' prayers and a derisive dissent from Justice Antonin Scalia.Is it time for Justice Scalia to bite his tongue?