LIKE PRESIDENT OBAMA, federal courts have been evolving on same-sex marriage.

In 1972, the Supreme Court summarily dismissed a challenge to a Minnesota law defining marriage as the union between a man and a woman, rejecting the notion that the Constitution’s equal protection clause guaranteed the right of same-sex couples to marry. Citing that standing precedent, the U.S. Court of Appeals for the First Circuit found that it could not proclaim such a right in 2012. Instead, the court issued Thursday a more limited but nevertheless important ruling in the long fight for same-sex marriage equality.

The Boston court overturned the most noxious part of the Defense of Marriage Act (DOMA) — which denies federal benefits to same-sex couples, regardless of whether gay marriage is allowed in their home states. The ruling redresses the grievous injustice of prohibiting benefits to the 100,000 same-sex couples now legally married. What’s more, it gives voters in Maryland more confidence that, should they approve of gay marriage in November, federal courts will guarantee same-sex couples’ access to everything from the ability to file taxes jointly to Social Security survivor benefits.

In writing for the court, Judge Michael Boudin said that Congress did not have sufficient ration­ale for DOMA. The act faces a slightly higher bar for constitutionality than other laws since it targets a minority group and puts pressure on states in a policy area typically reserved for them. Against that standard, the justifications for DOMA fail. Denying marriage benefits to gay men and lesbians does nothing to encourage or defend traditional, heterosexual marriage, for example. And it does nothing to promote child-rearing in “stable” heterosexual households, since gay men can still adopt in most states and lesbians can still bear children.

Still, Judge Boudin went out of his way not to condemn all of the law’s supporters, including President Bill Clinton, who signed DOMA in 1996 and has since called for its repeal. “Traditions are the glue that holds society together,” the judge wrote. “The desire to retain them is strong and can be honestly held.” He also suggested that the ruling could not be used as the basis for overturning state bans on same-sex marriage.

To gay activists weary after decades of effort to attain basic rights, the First Circuit’s decision will no doubt feel too cautious. We share their frustration that so many states continue to deny so many Americans a freedom as fundamental as the ability to wed. But this ruling is not the end of the cause in statehouses, voting booths or federal hearing rooms. It is just one, forward-facing step.

As the country has moved toward broader acceptance of gay marriage, so have the courts. We look forward to watching that process ­continue.