The US Supreme Court ruled in June 2013 that Section 3 of the Defense of Marriage Act (DOMA) 1996 is unconstitutional. This means that it is no longer permissible in the US to treat same-sex spouses differently from heterosexual spouses. The US government has since changed the law so that same-sex partners and spouses can now apply for US family-based immigrant visas.
DOMA was passed in 1996 with bipartisan support with the stated aim of "defending marriage". To that end, section 3 of DOMA denied certain federal benefits and legal rights to same sex spouses.