“RBG”

***

(PG, 1:37)

Ruth Bader Ginsburg was the second woman appointed to the U.S. Supreme Court, but she’s probably the first justice to become a full-fledged pop-cultural phenomenon. “RBG,” a loving and informative documentary portrait of Ginsburg during her 85th year on Earth and her 25th on the bench, is both evidence of this status and a partial explanation of how it came about.

Directed by Betsy West and Julie Cohen, the film is a jaunty assemblage of interviews, public appearances and archival material, organized to illuminate its subject’s temperament and her accomplishments so far. Though it begins with audio snippets of Ginsburg’s right-wing detractors — who see her as a “demon,” a “devil” and a threat to America — “RBG” takes a pointedly high road through recent political controversies. Its celebration of Ginsburg’s record of progressive activism and jurisprudence is partisan but not especially polemical.

The filmmakers share her convictions and assume that the audience will, too. Which might be true, and not only because much of the audience is likely to consist of liberals.

Before she was named to the federal bench by Jimmy Carter in 1980, the future justice argued a handful of important sex-discrimination cases in front of the Supreme Court. What linked these cases — she won five out of six — was the theory that the equal protection clause of the 14th Amendment should apply to women and could be used to remedy discrepancies in hiring, business practices and public policy.

The idea that women are equal citizens — that barring them from certain jobs and educational opportunities and treating them as the social inferiors of men are unfair — may not seem especially controversial now. “RBG” uses Ginsburg’s own experiences to emphasize how different things were not so long ago.

At Harvard Law School, she was one of nine women in a class of hundreds, and was asked by the dean (as all the women were) why she thought she deserved to take what should have been a man’s place.

THE BIOGRAPHICAL part of “RBG” tells a story that is both typical and exceptional. It’s a reminder that the upward striving of first- and second-generation Jewish immigrants in the middle decades of the 20th century was accompanied by fervent political idealism. Ginsburg’s career was marked by intense intellectual ambition and also by a determination to use the law as an instrument of change.

The film also chronicles her marriage to Martin Ginsburg. They met as undergraduates at Cornell, and for the next 63 years, Martin Ginsburg (who died in 2010) was his wife’s tireless supporter and champion, a man whose commitment to domestic egalitarianism was extraordinary in his time and far from common today. As their friends and children explain — and as Martin Ginsburg, a New York tax lawyer, often said himself — he was responsible for cooking meals and cracking jokes while she was making history. He also, when Byron White retired from the Supreme Court, made sure that her name was high on President Bill Clinton’s list of candidates.

It would be fascinating to learn more about that campaign, and also to have a finer-grained sense of the institutional and interpersonal dynamics of the court over the past quarter-century. But “RBG” reasonably chooses to focus on Ginsburg herself, and relishes every moment of her company. It also shows why she has become such an inspiration for younger feminists, like Irin Carmon and Shana Knizhnik, whose 2015 book “Notorious RBG: The Life and Times of Ruth Bader Ginsburg” helped created the contemporary image of a fierce, uncompromising and gracious champion of women’s rights.

That those rights are in a new phase of embattlement goes without saying. The movie’s touch is light and its spirit buoyant, but there is no mistaking its seriousness or its passion. Those qualities resonate powerfully in the dissents that may prove to be Ginsburg’s most enduring legacy. “RBG” is, above all, a tribute to her voice.