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. Justice 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, Mr. 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 Mr. 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 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 Justice 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 Justice Ginsburg’s most enduring legacy, and “RBG” is, above all, a tribute to her voice.