We initially found out that the lawsuit was going to be filed around May 2009. We approached the American Foundation for Equal Rights, who gave us permission to meet with Ted Olsen and David Boies, as well as the plaintiffs involved in the case. We said to them, "On the outside chance that this becomes something really important, can we film this for archival purposes and maybe someday make a documentary out of it?" They were gracious enough to let us film behind the scenes, and as the case snowballed we were right there alongside them. We had already been embedded with them for four years by the time we got to the Supreme Court.

We worked on the movie for three years without even knowing if it would become a finished film. If the case didn't end up before the Supreme Court, I don't know if someone like HBO would have come on board, and the film definitely wouldn't have had the epic third act that it does now. In December 2012, when the Supreme Court said it would hear the case, that's when we went into hyperdrive.

We spent a lot of time getting to know these people and trying to blend into the background. We wanted to be as unobtrusive as possible to their process. We'd slip in and out of rooms, sometimes in the middle of meetings. People got so used to us being there that eventually we were just allowed to be part of that process.

The plaintiffs were a little bit different. With the lawyers we were just asking to film their work lives, but with them it was their personal lives. It was definitely a process of making them feel comfortable with the fact that we would be following them. By year five we were doing a lot more following than in year one. They didn't sign up to be celebrities or stars of a documentary, so we were incredibly grateful with the access they and their families gave us. That's the heart of our narrative.

The American Foundation for Equal Rights spent a lot of time trying to find couples that were appropriate. Because same-sex marriage had been legal in California for several months in 2008, most of the people who were ready to get married at that point in their lives had already done so. So it was a bit of a challenge to find two couples who were not married but were looking to be. They met with a lot of people and wanted to find some who would also be good spokespeople in the press, and would do well on the stand. We're incredibly glad they picked Kris and Sandy and Jeff and Paul, since hearing them speak on the witness stand was one of the most moving days of our lives.

We show some of the plaintiff prep in the film for maybe five to 10 minutes, but that process went on for many grueling days. Each plaintiff had to go through it individually, having every moment of their life scrutinized under a microscope. You can imagine how uncomfortable that would be. But then it was powerful to watch that preparation translate to the witness stand. The moment in the film with Kris Perry reading her testimony ? that wasn't what they had prepared for. All those personal genuine feelings came out organically on the stand. Nothing we saw in the conference rooms matched that power.

We were there, but we weren't able to film it. Early on, District Chief Judge Walker had decided he wanted this case to be part of a trial program for broadcasting trials that had an effect on the wider public. That decision was made, and the proponents of Prop 8 appealed that decision all the way to the Supreme Court. On the first day of trial, the court issued a ruling that blocked the broadcast of the trial. The only way to experience it was to be in the courtroom, which is part of what made it so important to us to convey to people through this film what was happening in there.

Filming the legal process definitely isn't the most cinematic thing you can pick. We shot 600 hours of footage, and many of those hours are probably really boring stretches when we're just rolling a camera in a conference room, since we didn't know when an important phone call was going to come in or when a ruling might come down. On the flip side, by keeping the cameras on we were able to capture a lot of the exciting parts of the legal process, especially in a case like this with so many twists and turns. That was something we worked on in the editing room, to keep the legal process exciting for an audience of lawyers, but also for a general audience that's not intimately familiar with the law.

The legal thriller aspect is definitely what drew us to the case to begin with, but as we went on we realized that it's a love story, and a very joyous one. These guys are also really funny ? we were lucky that it had a lot of comedic elements, a lot of romantic elements, and all on that legal thriller background. We loved playing with and mixing those genres.

Obviously, the end of the film was very celebratory. You've gone on this journey with these two couples and their families, and you watch them achieve what they worked so hard to do for five years. But the film's very last card explains what the situation is in the rest of the country. We see the end as quite bittersweet. In some ways, we're hoping that people who live in the 31 states where same-sex marriage is still illegal can watch what happened with Proposition 8 and what those two couples did, and find inspiration. We're seeing that all over now, and in every one of those states there are lawsuits pending.

It's the most exciting thing ever. It's been really great to do the festival circuit the last six months, and we've been able to take the film to lots of places in the trenches in the fight for marriage equality. But to now to take it to this level, we're incredibly humbled that so many people are going to see this film. We hope that it reaches all types of people ? obviously we would love an LGBT audience ? but we're hoping straight people, religious people, people from all over the country with all types of backgrounds will watch the story of these four people.

They had very credible lawyers, and they put out as much evidence as they could. But we saw several of their expert witnesses drop out of the case. When they did depositions, their facts just weren't passing muster. You saw people like David Blankenhorn, who was a principal witness for the other side, come out after the case and say that he has changed his mind on the issue. When you strip away the political slogans and the religious arguments, there really is no rational reason for discrimination like this.

The marriage equality movement didn't begin with Proposition 8. It began decades before that with people who dedicated their lives to the cause. There were a lot of stories before Prop 8, and there will be a lot after. We hope that we told one chapter of this story and that we told it well and in a way that moves people.