As I’ve written about before, I grew up in the far West Village of New York City, near the site of the Stonewall Inn riots that launched the modern gay rights movement, and witnessed a good deal of anti-gay bigotry in the raw throughout my childhood. So today’s Supreme Court decision striking down the Defense of Marriage Act as unconstitutional has personal meaning for me.

What’s particularly striking, in light of the decades of struggle that have unfolded since the early 1970s — the long dark period in the closet, the underground gay clubs that were subsequently padlocked amid the AIDS crisis, the shameful refusal of public officials to acknowledge that crisis — is the ringing language of equality in the SCOTUS decision.

It is unequivocal in declaring DOMA (which denies federal benefits to same sex couples legally married in states) in violation of the Constitution’s guarantee of equal protection and due process, and in striking down DOMA as a deliberate effort to impose inequality on a selected class of American citizens.

What happened today is that a whole new legal framework has been created within which state level battles over marriage equality will now unfold. It’s not an overstatement to say that the language in today’s decision may help put state laws banning gay marriage on the path to extinction around the country.

The court also declined to rule on a California court’s previous ruling striking down Proposition 8 — the law defining marriage as between a man and a woman in that state — arguing it didn’t have standing. That clears the way for same sex marriage to be legal in California.

With gay marriage already legal in around a dozen other states plus Washington, D.C., the short term upshot of the two decisions is that states that are home to over one quarter of the U.S. population have now legalized gay marriage, according to prominent gay rights lawyer Richard Socarides. What’s more, all of those marriages now have federal recognition.

For gay rights, advocates, the key language in the decision is that which explicitly describes DOMA as an effort to impose unequal status on a class of citizens to whom states have granted equality, and that there is no “legitimate purpose” in doing so. IN a reference to the fact that the plaintiffs’ marriage was legitimate under New York law, the decision also says: “By seeking to injure the very class New York seeks to protect, DOMA violates basic due process and equal protection principles applicable to the federal government.”

The decision adds:

The federal statute is invalid, for no legitimate purpose overcomes the purpose and effect to disparage and to injure those whom the state, by its marriage laws, sought to protect in personhood and dignity. By seeking to displace this protection and treating other persons as living in marriages less respected than others, the federal statute is in violation of the Fifth Amendment.

“We got five votes for a strong equal protection standard, which is more than we could have hoped for,” Socarides says. “It’s a new day.”

While the court didn’t rule on Prop 8 because of standing, this language does suggest that the Court is prepared to strike down other state laws banning gay marriage as in violation of the equal protection clause. And gay rights advocates predict a wave of new lawsuits against such laws as a result.

“This will be a powerful weapon for attacking restrictions on marriage around the country,” Theodore Boutrous, who helped argue the case for the plaintiffs in the Prop 8 case, tells me. “In future lawsuits challenging marriage restrictions in states, litigants will use the language in today’s decision.”

Indeed, in his dissent, Scalia all but admits all of this to be the case:

By formally declaring anyone opposed to same-sex marriage an enemy of human decency, the majority arms well every challenger to a state law restricting marriage to its traditional definition. Henceforth those challengers will lead with this court that there is “no legitimate purpose” served by such a law, and will claim the traditional definition has “the purpose and effect to disparage and to injure” the “personhood and dignity” of same-sex couples.

Scalia meant this as a negative, but he’s absolutely right. There is still plenty of work to do, but today’s decision will, in fact, give a powerful new weapon to those who will now set about getting state laws banning gay marriage struck down as illegitimate and an affront to the “personhood and dignity of same-sex couples.”

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.