"How could you not want to make a documentary about Ruth Bader Ginsburg?" director Julie Cohen ponders.
"She has a history going back many decades that's largely unknown, even to a lot of her fans, of being at the forefront of fighting for women's equal rights. She's got an incredible love story and, on top of that, she's an 85-year-old woman who can do 20 push-ups. How can you not want to tell her story in a film?"
That film is RBG, a documentary three years in the making. It's an accessible, deep dive into the remarkable life of American Supreme Court judge and pop culture hero Ruth Bader Ginsburg.
"She's become this big rock star for the younger generation. She's popped up as an internet meme and people dress like her for Halloween. She's a unique figure," Cohen says. "A judge, but people get tattoos of her face on their arms."
It's through her pop culture status that most Kiwis will recognise Justice Ginsburg, mostly from the popular The Notorious RBG meme. She's become a hero of the left in the United States and a symbol of resistance against the abhorrent impulses of the Trump administration and his Republican supporters.
But, as Cohen says, and the documentary she co-directed with Betsy West shows, Ginsburg has been fighting the good fight for decades.
"She's had a huge impact, particularly for woman, on our place in society under the law. Basically, it was perfectly legal to discriminate against women. A bank was allowed to deny you a loan, you couldn't get a credit card or a mortgage on the house. Women could get fired for being pregnant and abortion was completely banned. It was viewed as constitutional for women to be denied reproductive rights.
"There was a whole package of laws that legally discriminated against women, and Justice Ginsburg was at the absolute forefront of the movement to say the US Constitution can be used to address these changes."
In the film, Ginsburg is often described as someone who doesn't like to "toot her own horn," and Cohen admits that getting her to take part was difficult.
"It took a fair amount of patience and cajoling on our part to get the Justice to cooperate with this project. We approached her in January of 2015 but her initial answer was 'not yet'."
As that wasn't an outright no, the film-makers asked for, and received, permission to interview people from Ginsburg's life - family, colleagues, and clients from her gender discrimination cases in the 70s.
"But she said to us she wouldn't be interviewed for at least another two years. The interview we ultimately did with her was a full two years after the time she said, 'two more years'. She stuck to that," Cohen says.
With Ginsburg's reputation preceding her, I ask how Cohen and West were feeling when they went to conduct their long-awaited interview.
"You're always nervous when you're with Justice Ginsburg," says Cohen. "She's an intimidating person. If she thinks what you've asked isn't the right thing to ask she'll let you know. Despite her teeny stature, she has a big, regal and intimidating presence. It's a bit nerve-racking."
But, once Ginsburg was in, she was all in. One of the more remarkable scenes shows the 85-year-old's workout routine. It's amazing that she allowed cameras to document this.
"It felt like a long-shot request and we were nervous about making it," Cohen says. "We were surprised and delighted when she agreed. We didn't know what to expect. A lot had been reported about her workout but no one had ever seen it. We'd heard she did planks and lifted weights and did 20 push-ups but, honestly, we did not believe it. We thought it was an urban legend."
Far from it. Steely-eyed and determined Ginsburg pushes past the wall to complete her intense and rigorous workout.
"It was far beyond what I'd be capable of doing," Cohen says. "It was really impressive and a lot of fun."
Starting at childhood and ending in the present day, the documentary does a fantastic job at showing how many barriers Ginsburg broke on her way to sitting at the highest court in the United States. It's an inspirational story.
"We've heard from viewers who say they started planking because of our film. We've also heard from others who said that they've taken the entrance exams for law school.
"Perhaps that will be the legacy of the film," says Cohen. "Older woman planking and younger women becoming attorneys... which wouldn't be such a bad outcome."
Who: Director Julie Cohen
What: Documentary RBG about Justice Ruth Bader Ginsburg
When: In cinemas next Thursday