On Monday, premium cable network HBO will broadcast The Case Against 8, which documents the case to overturn Proposition 8, California's now-ended ban on gay marriage.

The Case Against 8 premiered at the Sundance Film Festival, where it won the Directing Prize for U.S. Documentary.

With unlimited access to the plaintiffs and the lawyers involved in the case, filmmakers Ben Cotner and Ryan White give audiences a behind-the-scenes look at the case's many twists and turns on the road to the Supreme Court.

California voters approved Proposition 8 in 2008, sparking massive protests in California and Utah, home to the Mormon Church which played a key role in its passage.

The following year, two plaintiff couples – Kristin Perry and Sandy Stier and Paul Katami and Jeff Zarillo – challenged the amendment's constitutionally. It was the first such case filed in a federal court, which led to fears the Supreme Court would uphold the ban, possibly setting back the marriage movement decades. (The film's trailer is embedded on this page. Visit our video library for more videos.)

In speaking with BuzzFeed, Cotner said the film was not about marriage but rather the people behind the case.

“I think, for us, since we never wanted to make a film about whether gay marriage was right or wrong, for us, it was about telling the story,” said Cotner, who is gay and lives in California. “Once we got there, and got to know Kris and Sandy and Paul and Jeff, it became obvious that this is really a story about these four people's lives and how they were affected and the harms that were done by Proposition 8 to them – and there was so much in that that we related to.”

White added: “Whether it had been a win or loss, we were dedicated to just telling the story of what these people went through – and luckily it turned out the way it did.”