Elyse Steinberg, one of the co-directors of the new documentary “The Fight,” was inspired to learn more about the American Civil Liberties Union (ACLU) shortly after Donald Trump moved into in the White House.

“Seven days into Trump’s presidency,” she recalls, after the travel ban in Muslim-majority countries was issued in January 2017, “I joined the protestors on the steps of the Brooklyn courthouse.” That day, from a distance, she spotted Lee Gelernt, one of the lawyers arguing against the ban. He had a triumphant — and bewildered — look on his face as he walked outside, where he heard the crowd chanting: “ACLU! ACLU!”

“He was a person never expecting to be in the maelstrom,” Steinberg says. “And I immediately recognized that being next to this guy, fighting against Trump, was where we needed to be.”

After three years and more than 400 hours of footage, the result is “The Fight,” about the ACLU’s efforts to stand up against the Trump administration. The movie is one of the buzzier titles to debut at this year’s Sundance Film Festival, which is infused with an unusual dose of politics, from “Hillary” (a Hulu docu-series about Hillary Clinton) to “Us Kids” (about March for Our Lives).

“The Fight,” which premieres on Jan. 24 and is seeking distribution, is made by Steinberg, Josh Kriegman and Eli Despres, the filmmaking team behind “Weiner.” When they last came to Sundance, in January 2016, they had a richly detailed look at Anthony Weiner’s failed bid to become mayor of New York following an embarrassing sexting scandal.

“The Fight” is less comical, and more urgent — given that the group of ACLU lawyers featured in the film are arguing for such high-stakes cases as allowing immigrants to be reunited with their children or transgender Americans to continue serving in the military. “These are our Avengers,” says producer Kerry Washington, who helped secure financing for the project. “I wanted to go behind the scenes. I wanted to know their origin stories and root for them, as we do for all our Marvel superheroes.”

That wasn’t so easy to accomplish. When the directors initially pitched the ACLU on letting cameras follow them around all day, they were turned down. “We wanted total access,” Despres says. “We wanted to be on the inside, following every twist and turn. They told us they really appreciated the vision — thank you very much, but you’ll never be able to film here at the ACLU.”

Over time, the lawyers’ fears about the invasiveness of cameras crews started to thaw, especially given the important nature of the cases they were handling. “It was a lot of conversations over weeks and month,” says Kriegman.

Access was only the first hurdle. As Trump continued to enact polities that curbed the civil liberties of various groups of people, it wasn’t always clear what the narrative arc of the documentary would be. “Watching the footage as it was coming up, I was like, ‘How does this become a narrative?’” Washington recalls.

But eventually, the filmmakers landed on a story, as they learned more about the people tasked with holding the Trump administration accountable. In one scene, as Gelernt is prepping for a case, he can’t figure out how to charge his iPhone — and he fumbles with where to plug in the cord. “We really are interested in movies that people want to see, that don’t feel like medicine,” Despres says. “As heroes, we wanted the Peter Parker, not just the Spider-Man. That’s what the [lawyers] shared — the humanity of these characters, what it was like to save the world while getting their kid in a snowsuit.”

One of the messages of “The Fight” is just how drastically Trump has tried to disrupt the lives of so many people living in the United States. But at the same time, “The Fight” isn’t only about reminding voters of his policies prior to the next presidential contest.

“I think, beyond the next election, it’s about inspiring a different level of engagement from all citizens,” Washington says. “It really is about groups of people coming together to create change.”