“She knows the fact that she’s doing this, and embracing it, means so much to young women — because she’s teaching, every time she gives a speech or talks to people,” he said after the screening. “And that’s what this movie will do too. So she knows how valuable it is.”

Mr. Olson calls her a warrior. Ms. Steinem, in the documentary, calls her a superhero. (Marvel agrees: in “Deadpool 2,” when the title character is assembling his X Force, he flicks through a photo of her as a candidate.)

For Julie Cohen and Betsy West, the directors of “RBG,” she was, first off, a hard-to-wrangle subject. Each had interviewed her for other projects, but when they approached her about the documentary she told them she wouldn’t talk to them for at least two years. She was 82 at the time.

They persisted, interviewing colleagues and clients for whom she did landmark work. Eventually they were granted an audience with her, trailing along on family vacations, to the opera, and on a visit with her granddaughter, a recent Harvard Law graduate who calls her Bubbie. In her chambers, Justice Ginsburg traced her path from law school, where the dean asked her and the eight other female students (in a class of about 500) how they could justify taking the place of a man. Though she made the law review and graduated at the top of her class at Columbia, no firm would hire her, a Jewish woman and already a mother; she became a professor instead. If she felt any frustration at being shortchanged professionally, it didn’t erupt. “Reacting in anger or annoyance will not advance one’s ability to persuade,” she wrote in her 2016 autobiography, “My Own Words.”