In a 5-4 decision that split along partisan lines, the Supreme Court ruled on Wednesday morning in United States v. Windsor that the 1996 Defense of Marriage Act is unconstitiutional.
The majority opinion, written by Justice Anthony Kennedy, found that DOMA is a violation of the "equal protection" clause of the Fifth Amendment to the Constitution.
As a result of the Court's decision, same-sex marriages will be entitled to all federal benefits that heterosexual marriages already enjoy, but only in states in which same-sex marriage is legal.
The Defense of Marriage Act is a 1996 law signed by President Bill Clinton that defined marriage for legal purposes as the union between a man and a woman as husband and wife. Section 3 of the act, which the court considered in United States v. Windsor, barred federal benefits for same-sex couples, even in states where same-sex marriage is legal.
The plaintiff behind the Supreme Court challenge against DOMA is Edith Windsor, an 83-year-old lesbian woman.
After 40 years of romantic involvement with her partner, Thea Spyer, Windsor and Spyer married in Toronto, Ontario, in 2007. Both Windsor and Spyer were residents of New York, where Windsor first proposed engagement to Spyer in 1965.
In 2009, Spyer passed away, and Windsor was required to pay more than $363,000 in federal estate taxes on her inheritance of her wife's estate. She would have paid no federal state taxes had federal law accorded her marriage the same status as a heterosexual marriage.
Soon after her wife's death, Windsor decided to sue the government, claiming that it was unfair for her to be forced to pay such steep federal taxes. The United States Court of Appeals for the Second Circuit, in New York, struck down the Defense of Marriage Act as unconstitutional.
Following the Supreme Court's decision on Wednesday morning, Section 3 of the Defense of Marriage Act has been invalidated, although Section 2, which says that states do not have to recognize same-sex marriages from other states, still stands.
You can read the full opinion here.