Ruth Bader Ginsburg's early days portrayed in 'On the Basis of Sex'

LOS ANGELES (KABC) -- If you consider Supreme Court Justice Ruth Bader Ginsburg a superhero then a new movie about her would be her origin story.

"On The Basis Of Sex" is inspired by Ginsburg's early days, including her passion for equality and women's rights.

Her nephew, Daniel Stiepleman, wrote the script.

"Her mantra was, if you're going to make a portrait of me, just make it an accurate portrait," said Stiepleman. "Most of the best ideas from the film came out of going through her files from the Library of Congress from the '60s and '70s and reading just these little minutiae that she wrote in the margins of cases and letters that she received from other people. And most of the story was built out of that."

Felicity Jones plays the young future Supreme Court justice.

"She believes deeply in the law, believes deeply in America," said Jones. "Daniel used to say that his aunt would give him copies of the U.S. Constitution to carry around in his bag. So she holds it very dear to her heart."

Justin Theroux, who plays former ACLU legal director Mel Wulf, says being part of this movie was an education.

"I learned tons of stuff," said Theroux. "I didn't know that women couldn't rent cars without their husbands present. I didn't know that women were seriously blocked from an enormous amount of job opportunities. I didn't know that they couldn't get credit cards in their own name."

"I was at a screening two nights ago in New York and just as the movie ended, this woman sitting on the aisle said, 'I think I'm crying.' And then the woman next to her said, 'That's OK. So am I,' and they hugged," said Stiepleman. "But my favorite thing about it that then after they hugged, they introduced themselves to each other."

"On The Basis of Sex" is in theaters now.