The case emanates from Edith Windsor, an 83-year-old lesbian who sued the federal government for charging her more than $363,000 in estate taxes after being denied the benefit of spousal deductions.
The 2nd U.S. Circuit Court of Appeals determined Thursday that the federal law violates the Constitution’s equal protection clause.
The ruling upholds a similar decision made in a federal appeals court in Boston and provides momentum for those seeking to strike down the law. The case will probably culminate in a U.S. Supreme Court decision.
In February 2012, the Obama administration ordered the Justice Department to stop defending the constitutionality of the law.
Currently, Massachusetts, Connecticut, Iowa, Vermont, New Hampshire, New York, and the District of Columbia issue marriage licenses to same-sex couples.
Maryland, Washington, Maine, and Minnesota are voting on the issue in November referendums.
Five states – Delaware, Hawaii, Illinois, New Jersey, and Rhode Island – currently allow civil unions that provide rights similar marriage.