The Supreme Court’s marriage equality rulings, announced Wednesday morning, are cause for celebration for all Americans across the political spectrum.

In United States v. Windsor, a sweeping 5-4 ruling authored by Justice Anthony Kennedy, the Supreme Court struck down Section 3 of the “Defense of Marriage Act” (“DOMA”), which denies federal recognition to state-recognized same-sex marriages, holding that the Constitution prohibits the federal government from treating married same-sex couples as second class citizens.

In Hollingsworth v. Perry, another 5-4 ruling, the Court held that proponents of California’s Proposition 8 lacked standing to appeal a federal trial court’s judgment that California’s Proposition 8 violates the Fourteenth Amendment rights of gay men and lesbians.  As a result of the rulings, Proposition 8 and Section 3 of DOMA are null and void.

The essential point at the heart of Justice Kennedy’s opinion is that the Constitution’s promise of equality protects all persons, including gay men and lesbians, from invidious discrimination by the government.

Justice Kennedy’s opinion for the Court affirmed that the Constitution “withdraws from Government the power to degrade or demean,” holding DOMA’s regime of federal discrimination unconstitutional for the simple reason that “DOMA writes inequality into the entire United States Code.”

Justice Kennedy’s opinion relied both on principles of federalism and individual liberty and equality, emphasizing the many ways in which DOMA’s vast regime of discrimination “interfere[s] with the equal dignity of same-sex marriages, a dignity conferred by the States in the exercise of their sovereign power.”

Justice Kennedy’s opinion held Section 3 of DOMA unconstitutional based on a violation of individual rights, not a lack of federal power or invasion of state sovereignty.

Federalism works in service of the Constitution’s universal protection of equality, a guarantee Justice Kennedy rooted both in the Due Process Clause of the Fifth Amendment and the Equal Protection Clause of the Fourteenth Amendment, which, Kennedy explains, “makes that Fifth Amendment right all the more specific and all the better understood and preserved.”

Justice Kennedy, quite properly, treats DOMA’s vast system of marriage discrimination as a frontal assault on the Constitution’s universal guarantee of equality, explaining that DOMA’s “principal purpose is to impose inequality” by placing “same-sex couples in an unstable position of being in a second-tier marriage.”  This rank discrimination, he continued, “demeans the couple, whose moral and sexual choices the Constitution protects, and whose relationship the State has sought to dignify.”

The majority’s strong affirmation of the basic constitutional ideal of equality under the law contrasts sharply with the dissenters’ utterly cramped understanding of the constitutional principle of equality.   Just a day after inventing a constitutional right of state equality to strike down a core part of the Voting Rights Act, Chief Justice Roberts and the other dissenters would permit the government to enact a massive regime of discrimination against gay and lesbian married couples based on interests in “uniformity,” “stability,” and “avoid[ance of] difficult [legal] issues.”

Justice Alito’s dissent dismissed the Court’s equal protection framework outright, arguing that the case turned not on the meaning of equality, but on “what marriage is.”  None of the dissenters made any real effort to square DOMA with the constitutional ideal of equality under the law.

The Windsor ruling, of course, did not decide whether states may forbid same-sex marriage, and the Court held in Perry that it lacked jurisdiction to decide the constitutionality of Proposition 8’s ban.  That issue is still a live one.  But, by affirming the Constitution’s promise of equality for all persons, today’s sweeping ruling in Windsor establishes a strong constitutional foundation for marriage equality.

David H. Gans is the Director of Constitutional Accountability Center’s Human Rights, Civil Rights and Citizenship Program and a co-author of amici briefs filed in Windsor and Perry on behalf of the Cato Institute and the Constitutional Accountability Center.