"All deliberate speed" — that was the gradualist coda the U.S. Supreme Court added in 1955 to its second Brown v. Board of Education ruling after it ended school segregation. In striking down the Defense of Marriage Act without establishing a general constitutional right for gay people to marry, the court did the same thing for same-sex marriage that it once did for segregation: declared a principle without putting it fully into practice.

In Brown, the court's goal of making desegregation palatable failed when Southern whites mounted widespread resistance. Whether the same strategy will work better this time remains to be seen, but it certainly sets the stage for many legal and political battles over gay marriage in the years ahead.

The big principles Justice Anthony Kennedy declared in his U.S. v. Windsor opinion (which was joined by the four Democratic-appointed justices) lived up to the standard he set in the landmark gay-rights cases of Romer v. Evans and Lawrence v. Texas. In short, Kennedy wrote, DOMA was an affront "the equal dignity of same-sex marriages."

DOMA was unconstitutional because it was intended to "disparage and to injure those whom the State, by its marriage laws, sought to protect in personhood and dignity."

Constitutional Touchstones

The idea that every human has a basic right to dignity and personhood doesn't appear in the text of the Constitution, either in the equal protection clause (which by its language applies only to the states, not the federal government) or in the due process clause of the Fifth Amendment, which does apply to the federal government and has been taken to incorporate equal protection. Through Kennedy's opinions on reproduction, sex and now marriage, however, dignity and personhood have become undeniable constitutional touchstones.

This is Kennedy's legacy. The Windsor decision will join Casey v. Planned Parenthood, which upheld Roe v. Wade, and Lawrence v. Texas, which protected gay sex, in the pantheon of grand declarations on the meaning of liberty. (Although all these opinions go against current Catholic moral teaching, careful readers of the future will note that Kennedy's ideals of dignity and personhood resonate strongly with the language of his church's moral theology since Vatican II.)

Beyond the abstractions, things get complicated quickly. The DOMA decision means that gay couples married in states that recognize their union will get full federal benefits. But what will happen to same-sex marriages in states that don't recognize them? And, if same-sex marriages are now entitled to "equal dignity" under the Constitution, can some states continue to deny people of the same sex to wed?

Justice Antonin Scalia, in his stinging dissent — he called the court "hungry" to announce its holding and said that the decision's "diseased root" lay in its aggrandized notion of its own role — also made the point that the opinion gave no guidance on how lower courts should interpret such questions in the cases that lie ahead.

Today's other big ruling, on California's voter-approved ban on same-sex marriage, gave the court a chance to resolve these matters by squarely considering whether a state could deny gay couples the name "marriage" even while providing marriage- like rights. Instead, in a bizarre 5-4 split, with Chief Justice John Roberts writing for a majority that included Scalia and the liberals Ruth Bader Ginsburg, Stephen Breyer and Elena Kagan, the court said it lacked the authority to rule on Hollingsworth v. Perry because the state of California had declined to argue that the law was constitutional. The law's supporters, Roberts explained, lacked standing because they themselves hadn't been ordered by any court to do or abstain from doing anything. A general interest in vindicating the law passed by the public wasn't enough.

Bizarre Coalition

This coalition of justices who didn't want the court to announce (or deny) a basic right to same-sex marriage wasn't the only bizarre crossing of ideological lines. Kennedy's dissent, urging that the issue should have been resolved, also spoke for a weird group of four, with the liberal Sonia Sotomayor and the conservatives Samuel Alito and Clarence Thomas joining. It will take some time to figure out whose motivations went where. But the effect of the 5-4 ruling was to stop short of a general declaration of a right to gay marriage.

We can say with some confidence that if Kennedy had been willing to declare such a general right, all four liberals who joined him in Windsor would have come along. The implication is that Kennedy wanted to do something short of that, and that Ginsburg, Breyer and Kagan thought it would be better for the court to say nothing about the California law than to uphold it. This opened the door for Roberts to write an opinion calling for judicial restraint, his emerging core value after last year's decision on the Affordable Care Act.

The upshot is something very much like the gradualism of the second Brown decision, when the court declared that its ban on segregation should be put into effect "with all deliberate speed." Critics said this was a terrible idea from the start, and they were proved right when resistance mounted and desegregation lagged. Social controversy wasn't averted but rather encouraged by the court's impulse to go slow.

We won't see federal troops in the streets this time, but there is reason again to doubt whether we will see a gradual acceptance of same-sex marriage or a redoubled effort by its opponents to keep it from becoming the norm nationally. Certainly, lawsuits will be filed immediately, arguing that the equal dignity of marriage requires states to respect each other's marriages, and even to allow their own gay citizens to marry. The issue is going to become more fraught in the next few years as it works its way through the courts, not less.

Brown has gone down as a great opinion poorly implemented, inspirational in principle and deeply flawed in practice. I suspect Windsor and Perry combined will leave the same legacy.

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Noah Feldman, a law professor at Harvard University and the author of "Cool War: The Future of Global Competition," is a Bloomberg View columnist.