Two new lawsuits challenging the 1996 Defense of Marriage Act (DOMA), which restricts federal marriage benefits to heterosexual couples, were filed in federal court Tuesday on behalf of same-sex couples in New York, Connecticut, Vermont and New Hampshire.

The suits were filed by the gay rights legal advocacy group Gay and Lesbian Advocates and Defenders (GLAD) and the American Civil Liberties Union (ACLU). GLAD filed a similar lawsuit earlier this year, which led to U.S. District Judge Joseph Tauro’s July ruling that found DOMA unconstitutional.

According to The New York Times, GLAD’s suit involves Joanne Pedersen and her wife, Ann Meitzen, who has been denied spousal benefits under Ms. Pedersen’s federal health insurance.

The Times reports that the ACLU suit stems from a $350,000 federal estate tax that Edith Windsor was forced to pay when her wife, Thea Spyer, died last year. Heterosexual couples are not required to pay estate taxes when one spouse dies.

Mary Bonauto, director of the Civil Rights Project for GLAD, told the Times that same-sex couples “are falling through the safety net other people count on.” Bonauto went on to point out that denying gay couples the federal rights that accompany marriage deprives them equal protection under the law, which is guaranteed by the Fourteenth Amendment of the U.S. Constitution.