By Lindsey Bahr, Film Writer

LOS ANGELES (AP) --

The Ruth Bader Ginsburg film "On the Basis of Sex" was about to fall apart when Felicity Jones got her hands on the script. The origin story about the future Supreme Court justice written by Ginsburg's nephew Daniel Stiepleman had been in various stages of development since 2012, looking for the right star (Natalie Portman was originally attached), the right director (Mimi Leder could only do it after finishing the third season of the HBO show "The Leftovers") and the right time to finally hit go. But it was looking wobbly again and they needed an answer fast.

The British actress, fresh off the Star Wars film "Rogue One," had been looking for a project about a woman and her career and had recently become familiar with Justice Ginsburg, whose celebrity has only grown of late. And Ginsburg, who had seen Jones in her Oscar-nominated role in "The Theory of Everything," had already given her informal approval to cast Jones. ("I think the only thing she was nervous about was getting rid of that English accent," laughed Leder.)

Jones read it in a weekend, said yes, and, finally, the stars had aligned. The film was happening.

"I didn't take it on lightly" Jones said despite her quick answer. "It was really intimidating at first, like gosh how do I do justice to this person?"

Ginsburg didn't have advice for Jones when they met ("She said, 'I've seen your work and I know you can do it,'" Jones said.) But she did have one request for the filmmakers: That they would be absolutely precise in capturing the law. Can you blame her?

"On the Basis of Sex," in theaters nationwide on Christmas Day, caps off a big year for Ginsburg in cinema that started with the documentary "RBG" premiering at Sundance last January and going on to become a modest box-office phenomenon.

This film is complimentary to the documentary, and focuses in on two very specific parts of Ginsburg's early days in law long before she would go on to be confirmed as an associate justice in 1993: First as one of the few female students at Harvard Law School in the mid-1950s, and then as a professor at Rutgers in the 1960s, when she started getting involved with gender discrimination cases with the American Civil Liberties Union.

It not only shows Ginsburg's incredible work ethic and instances of the adversity she faced from both her professors and potential employers, but also her happy home life with her children and her supportive husband Martin (or Marty) Ginsburg, who died in 2010. He is played by Armie Hammer.

"It's very much about showing how someone becomes the icon that they are today. She didn't come out fully formed at 85. You see the struggle it takes," Jones said. "She was constantly put in situations where she had to battle on every front, with her faith, with her gender, where she was from."

It helped inform how Jones, 35, would craft Ginsburg's voice, which in those days, at least publicly, was more Mid-Atlantic than the heavier Brooklyn accent many are familiar with today.

"When she's frustrated her more Brooklyn vowel sounds come out because she can't help but say it in her more kind of natural voice," Jones said. "It's interesting to show just how her public-self had to become something that was quite separate from her private-self."

Although she's of a quite different generation than Ginsburg, Jones did relate in her own way to feeling like the only woman in the room, especially on film sets where most of the crew are male. ("I would love to ideally walk out on a set and see half men and half women in all of the roles behind the camera," Jones said.)

Leder, at 66, is of yet another generation, but also found commonalities with Ginsburg, as a trailblazer in her own industry. She was the first woman to be in the cinematography track at the American Film Institute, and like her contemporary Kathryn Bigelow, would go on to direct bigger budget action films like "Deep Impact" and "The Peacemaker" at a time when very few women were making those kinds of movies.

"I never compare myself to her accomplishments, but I connected to RBG in a very personal way," Leder said. "We're both mothers, both Jewish, both have (had) longstanding marriages and know what that takes. And both have broken the glass ceiling in different ways and paved the way for others for generations to come."

A master at creating tension, Leder brings urgency to staid courtroom scenes fitting of her action-film background.

Jones observed that it has elements of a sports film too with its arc of an outsider and underdog finding her voice and power.

"We wanted it to be fun and entertaining. We go to the cinema not only to think about the world in a different way but to have a nice two hours," Jones said. "I hope that people enjoy the humor of it and enjoy the experience of it and say actually, you know what, I might be able to change the world too."

MySHOOT Profiles