In a 5-4 decision, the Supreme Court struck down Section 3 of the Defense of Marriage Act, ruling that it is unconstitutional to prohibit the federal government from recognizing same-sex marriages.
As it stood, the law denied same-sex married couples federal benefits, such as Social Security and the ability to file joint tax returns.
"DOMA is unconstitutional as a deprivation of the equal liberty of persons that is protected by the Fifth Amendment," Justice Anthony Kennedy wrote for the majority.
The impact of the DOMA case, United States v. Windsor, is clear for the nation's approximately 130,000 legally married same-sex couples who were previously denied federal benefits under Section 3. That provision impacts around 1,100 federal laws, including veterans' benefits, family medical leave and tax laws.
The High Court also turned away defenders of California's Proposition 8, clearing the way for same-sex marriage to resume in the state.
Read more at CBS News.