Same-sex marriage advocates rally on the steps of the Supreme Court, June 26, 2013.
The ACLU of Virginia says it will file a federal lawsuit challenging the state's gay marriage ban.
Tuesday's announcement comes less than two weeks after the U.S. Supreme Court struck down a key provision of the federal same-sex marriage ban and left intact a lower court ruling overturning California's gay marriage ban.
Virginia voters in 2006 approved a constitutional amendment prohibiting same-sex unions and refusing to recognize such marriages performed in other states.
The ACLU says it will team with the gay-rights group Lambda Legal to argue that Virginia's ban violates the constitutional guarantee of equal protection under the law. The organization also is challenging gay marriage prohibitions in some other states.