LOS ANGELES — HBO on Tuesday announced a documentary film project that will chronicle the court battle to overturn California’s ban on same-sex marriage.

HBO said that two directors, Ben Cotner and Ryan White, have for years had exclusive behind-the-scenes access to the legal team that argued the recent Supreme Court case over Proposition 8, a California ballot initiative that banned gay marriage in the state. The Supreme Court late last month declined to rule on the case, effectively ending the ban.

The still-untitled documentary will be completed by the end of the year and make its debut on HBO sometime next year. Michael Lombardo, HBO’s programming president, in a statement called the movie “the story of a modern-day American revolution” and said it was intended to be “the film of record on this landmark case.”

Mr. Cotner, a first-time director, and Mr. White, known for the documentary “Good Ol’ Freda,” about the woman who served as secretary to the Beatles, gained access to the Proposition 8 legal team – led by the liberal David Boies and conservative Theodore B. Olson – through the American Foundation for Equal Rights, the nonprofit group that brought the challenge.