The 2nd U.S. Circuit Court of Appeals in New York slammed another nail in the coffin of the so-called Defense of Marriage Act on Thursday. The noxious 1996 federal law defines marriage as being between one man and one woman, thus denying same-sex families the right to marry and the same financial and legal stability afforded straight couples who marry. It’s flat-out discrimination. And by a 2-to-1 vote, the appeals court agreed.

The majority opinion in Windsor v. United States, written by Judge Dennis Jacobs, ruled that DOMA violated the Constitution’s guarantee of equal protection under the law. The conservative jurist appointed by President George H. W. Bush in 1992 even adopted the view of the Obama administration in declaring that laws singling out gay men and lesbians deserve “heightened scrutiny” by the courts.

In this case, all four factors justify heightened scrutiny: A) homosexuals as a group have historically endured persecution and discrimination; B) homosexuality has no relation to aptitude or ability to contribute to society; C) homosexuals are a discernible group with non-obvious distinguishing characteristics, especially in the subset of those who enter same-sex marriages; and D) the class remains a politically weakened minority.

This rationale was the basis for the Justice Department determination that DOMA is unconstitutional and that it would no longer defend the statute against legal challenge. And Jacobs’s use of “heightened scrutiny” is a first for an appellate court and goes a step farther than the May ruling from the Boston federal appeals court that also found DOMA unconstitutional in Gill v. Office of Personnel Management.

Edith Windsor, center, is interviewed at the offices of the New York Civil Liberties Union, in New York Thursday. (Richard Drew/AP)

Windsor v. United States is the case of Edith Windsor. She and Thea Spyer had been together 42 years when they legally married in Canada in 2007. But when Spyer died in 2009, Windsor had to pay federal estate taxes totaling $363,053 because DOMA prevents the Internal Revenue Service from recognizing Windsor as a surviving spouse. Windsor sued to get her money back.

The Windsor and Gill cases are not seeking any kind of special rights. The couples involved in these cases were legally married. They just want their unions recognized by the federal government. Something DOMA precludes. The Supreme Court will decide next month whether it will take up either or both of these cases in the current term.

“We are at a monumental tipping point as the Supreme Court stands poised to review a law that has resulted in treating gays and lesbians as second-class citizens,” Human Rights Campaign President Chad Griffin told me yesterday.

As for Proposition 8, which made California’s marriage equality law illegal and wrote discrimination into the Golden State’s constitution, the high court might take a pass. And if it does, the 9th Circuit Court of Appeals’ decision that Prop 8 is unconstitutional would stand. Same-sex couples could be able to marry there within weeks of the Supreme Court’s decision.

On Nov. 6, voters in Maryland, Maine, Minnesota and Washington State will vote on marriage equality. The prospects look good in Maine. They look really good in Maryland. According to The Post poll released yesterday, same-sex marriage is favored 52 percent to 43 percent. Polling on this question can be deceiving. Opposition to marriage equality is usually understated.

“The share of voters in pre-election surveys saying they will vote to ban same-sex marriage is typically seven percentage points lower than the actual vote on election day,” wrote New York University professor Patrick Egan in a 2010 study of same-sex marriage ballot measures between 1998 and 2009. But he went on to say, “By contrast, survey estimates of the proportion of voters intending to vote against same-sex marriage bans tend to be relatively accurate predictors of the ultimate share of ‘no’ votes.” If this trend holds up, Maryland could become the eighth state, plus the District of Columbia, to legalize marriage equality.

DOMA and the discrimination it perpetuates are doomed. It’s only a matter of time before DOMA is repealed by the people or the courts. While support for same-sex marriage is growing by the day, I strongly believe the rights of a minority should never be put to a public referendum. That’s why my hopes for equal protection under the law rest with the courts. The rulings in the 1st, 2nd and 9th Circuits buoy those hopes.

“Judges appointed by presidents from Nixon to Reagan to Bush I and II all agree — the Defense of Marriage Act’s ‘gay exception’ serves no legitimate government purpose and violates the Constitution,” said Evan Wolfson of Freedom to Marry. “The Supreme Court should swiftly affirm what this conservative judge held, and get the federal government back to treating all married couples — gay or non-gay — as what they are: married.”