This case involves the constitutionality of Proposition 8 (the "California Marriage Protection Act"), a referendum that amended the California Constitution to provide that legal marriages can only be between a man and a woman.  A federal district court ruled that Proposition 8 violated the Due Process and Equal Protection Clauses of the U.S. Constitution.  Same-sex marriage opponents appealed that ruling to the U.S. Court of Appeals for the Ninth Circuit. 

On October 25, 2010, Americans United, in conjunction with the Howard University School of Law Civil Rights Clinic, submitted an amicus brief in support of the district court's ruling.  The brief advocates for recognition of the constitutionality of the fundamental right to marry for same-sex couples by drawing various parallels between past opposition to interracial marriage and contemporary opposition to same-sex marriage.  The brief observes that just as with interracial unions, opponents of gay marriage point to perceived threats to social order and the institutions of marriage and family, rely on pseudoscientific and religious notions that same-sex unions are unnatural, and assert that same-sex parenting will result in physical and psychological harm to children.  Just as these arguments proved false and baseless in the context of interracial marriage, the brief contends, so too should they be rejected by Ninth Circuit in the context of same-sex marriage. 

On December 6, 2010, the Ninth Circuit heard oral argument.  On January 4, 2011, the court certified to the California Supreme Court a question concerning the standing of the Proposition 8 proponents under California law:  whether the proponents "possess either a particularized interest in the initiative's validity or the authority to assert the State's interest in the initiative's validity, which would enable them to defend the constitutionality of the initiative upon its adoption or appeal a judgment invalidating the initiative, when the public officials charged with that duty refuse to do so."  The California Supreme Court has not yet responded to the request.