Vermont is the latest state to join the fight against DOMA, or the Defense of Marriage Act, which seeks to define marriage as between one man and one woman.
Vermont has joined New York and Connecticut in filing briefs in a case brought by 83-year-old Edie Windsor, a New York woman who was required to pay $350,000 in estate taxes when her partner died, LGBTQ Nation reported.
Last year, the federal government agreed to stop defending DOMA, the Associated Press reported. The federal court of Massachusetts, among others, has already ruled the legislation unconstitutional.
More from GlobalPost: Defense of Marriage Act ruled unconstitutional by appeals court
145 house Democrats, including Nancy Pelosi, also filed a brief targeting the bill on Friday, which was signed into law by then-President Bill Clinton in 2001, the Huffington Post reported.
According to a poll by University of Minnesota Law School, 7 out of 10 constitutional law professors believe the federal Defense of Marriage Act is unconstitutional, and 87 percent support same-sex marriage, the Wall Street Journal reported.
54 percent said the federal Constitution requires states to recognize gay marriages.