The opinion of the majority begins by deconstructing and demonstrating the flaws in the Bowers v Hardwick decision. Justice Kennedy:

It must be acknowledged, of course, that the Court in Bowers was making the broader point that for centuries there have been powerful voices to condemn homosexual conduct as immoral. The condemnation has been shaped by religious beliefs, conceptions of right and acceptable behavior, and respect for the traditional family. For many persons these are not trivial concerns but profound and deep convictions accepted as ethical and moral principles to which they aspire and which thus determine the course of their lives. These considerations do not answer the question before us, however. The issue is whether the majority may use the power of the State to enforce these views on the whole society through operation of the crimi-nal law. "Our obligation is to define the liberty of all, not to mandate our own moral code." Planned Parenthood of Southeastern Pa. v. Casey, 505 U. S. 833, 850 (1992).

...

Equality of treatment and the due process right to demand respect for conduct protected by the substantive guarantee of liberty are linked in important respects, and a decision on the latter point advances both interests. If protected conduct is made criminal and the law which does so remains unexamined for its substantive validity, its stigma might remain even if it were not enforceable as drawn for equal protection reasons. When homosexual conduct is made criminal by the law of the State, that declaration in and of itself is an invitation to subject ho-mosexual persons to discrimination both in the public and in the private spheres. The central holding of Bowers has been brought in question by this case, and it should be addressed. Its continuance as precedent demeans the lives of homosexual persons.

...

Bowers was not correct when it was decided, and it is not correct today. It ought not to remain binding precedent. Bowers v. Hardwick should be and now is overruled. [emphasis added]

...

The petitioners are entitled to respect for their private lives. The State cannot demean their existence or control their destiny by making their private sexual conduct a crime. Their right to liberty under the Due Process Clause gives them the full right to engage in their conduct without intervention of the government. "It is a promise of the Constitution that there is a realm of personal liberty which the government may not enter." Casey, supra, at 847. The Texas statute furthers no le-gitimate state interest which can justify its intrusion into the personal and private life of the individual.

...

Had those who drew and ratified the Due Process Clauses of the Fifth Amendment or the Fourteenth Amendment known the components of liberty in its mani-fold possibilities, they might have been more specific. They did not presume to have this insight. They knew times can blind us to certain truths and later generations can see that laws once thought necessary and proper in fact serve only to oppress. As the Constitution endures, persons in every generation can invoke its principles in their own search for greater freedom.

...

The judgment of the Court of Appeals for the Texas Fourteenth District is reversed, and the case is remanded for further proceedings not inconsistent with this opinion.

It is so ordered.

Justice O'Connor joined in the majority opinion but dissented from overturning Bowers. She had originally voted with the majority in Bowers and evidently didn't wish to reverse her earlier decision, though former Justice Powell, who had originally sided with the majority much later said he regretted his decision.

Some quotes from O'Connor's opinion:

And the effect of Texas' sodomy law is not just limited to the threat of prosecution or consequence of conviction. Texas' sodomy law brands all homosexuals as criminals, thereby making it more difficult for homosexuals to be treated in the same manner as everyone else. Indeed, Texas itself has previously acknowledged the collateral effects of the law, stipulating in a prior challenge to this action that the law "legally sanctions discrimination against [homosexuals] in a variety of ways unrelated to the criminal law," including in the areas of "employment, family issues, and housing." State v. Morales, 826 S. W. 2d 201, 203 (Tex. App. 1992).

...

This case raises a different issue than Bowers: whether, under the Equal Protection Clause, moral disapproval is a legitimate state interest to justify by itself a statute that bans homosexual sodomy, but not heterosexual sodomy. It is not. Moral disapproval of this group, like a bare desire to harm the group, is an interest that is insufficient to satisfy rational basis review under the Equal Protection Clause. See, e.g., Department of Agriculture v. Moreno, supra, at 534; Romer v. Evans, 517 U. S., at 634 635. Indeed, we have never held that moral disapproval, without any other asserted state interest, is a sufficient rationale under the Equal Protection Clause to justify a law that discriminates among groups of persons. [emphasis added]

...

Texas argues, however, that the sodomy law does not discriminate against homosexual persons. Instead, the State maintains that the law discriminates only against homosexual conduct. While it is true that the law applies only to conduct, the conduct targeted by this law is con-duct that is closely correlated with being homosexual. Under such circumstances, Texas' sodomy law is targeted at more than conduct. It is instead directed toward gay persons as a class. "After all, there can hardly be more palpable discrimination against a class than making the conduct that defines the class criminal." Id., at 641

...

Indeed, Texas law confirms that the sodomy statute is directed toward homosexuals as a class. In Texas, calling a person a homosexual is slander per se because the word "homosexual" "impute[s] the commission of a crime." Plumley v. Landmark Chevrolet, Inc., 122 F. 3d 308, 310 (CA5 1997) (applying Texas law); see also Head v. Newton, 596 S. W. 2d 209, 210 (Tex. App. 1980). The State has admitted that because of the sodomy law, being homosexual carries the presumption of being a criminal [emphasis added]. See State v. Morales, 826 S. W. 2d, at 202 203.

...

A law branding one class of persons as criminal solely based on the State's moral disapproval of that class and the conduct associated with that class runs contrary to the values of the Constitution and the Equal Protection Clause, under any standard of review. I therefore concur in the Court's judgment that Texas' sodomy law banning "deviate sexual intercourse" between consenting adults of the same sex, but not between consenting adults of different sexes, is unconstitutional.

The dissent in this case seems to blather on about how the court shouldn't reverse itself, and spews a great deal of legaleze. Funny how complete reversal of an earlier decision for less reason than was present in this case didn't seem to bother them in Payne v Tennessee (in which the late Justice Thurgood Marshall wrote, "Power, not reason, is the new currency of this Court's decisionmaking. Four Terms ago, a five-Justice majority of this Court held that 'victim impact' evidence of the type at issue in this case could not constitutionally be introduced during the penalty phase of a capital trial. ... Nevertheless, having expressly invited respondent to renew the attack, 498 U.S. 1076 (1991), today's majority overrules Booth and Gathers and credits the dissenting views expressed in those cases. Neither the law nor the facts supporting Booth and Gathers underwent any change in the last four years. Only the personnel of this Court did.")

---Nick