WASHINGTON – In a historic argument for gay rights, President Barack Obama on Thursday urged the Supreme Court to overturn California’s same-sex marriage ban and turn a skeptical eye on similar prohibitions across the country.

The Obama administration’s friend-of-the-court brief marked the first time a U.S. president has urged the high court to expand the right of gays and lesbians to wed. The filing unequivocally calls on the justices to strike down California’s Proposition 8 ballot measure, although it stops short of the soaring rhetoric on marriage equality Obama expressed in his inaugural address in January.

California is one of eight states that give gay couples all the benefits of marriage through civil unions or domestic partnership, but don’t allow them to wed. The brief argues that in granting same-sex couples those rights, California has already acknowledged that gay relationships bear the same hallmarks as straight ones.