The notion of Ruth Bader Ginsburg, the diminutive and soft-spoken Supreme Court justice, as a judicial "rock star" - at least in the eyes of progressives who love her sharply worded dissents to opinions rendered by the increasingly conservative court - may seem a strange one. But the lively and thorough profile painted of her by the documentary "RBG," in which she is described in just those terms, makes a persuasive argument for that characterization. Now 85, Ginsburg is viewed by liberals, anxious about her advanced age and the rightward drift of the court, as a champion of the left, a bastion of resistance whose absence will be a loss for progress.Ginsburg, for her part, says she has no immediate plans to retire. And, when asked whether she regrets not having stepped down while President Barack Obama still had the chance to nominate a replacement, she says only that she has always believed that she should stay on as long as she is able. And is she able? What about the infamous footage of her seeming to drift off during the 2015 State of the Union address?Cue the shots of Ginsburg doing push-ups.Directors Julie Cohen and Betsy West mark the 25th anniversary of Ginsburg’s high court confirmation hearing by including excerpts from that 1993 Senate grilling, along with snippets of a 2017 panel discussion moderated by Nina Totenberg of NPR and more recent interviews. These rather conventional documentary components are supplemented by talking-head interviews with colleagues and friends, footage of her working out with her personal trainer and, most interestingly, archival audio from some of the cases that Ginsburg argued, as an attorney, before the Supreme Court.Madame Justice, of course, would probably politely but firmly dispute that she is, in any way, an icon of cool, as she does while watching - on camera, for the first time - Kate McKinnon’s impersonation of her on SNL. Giggling adorably at the actress’s "Weekend Update" impression as the trash-talking "Notorious RBG," Ginsburg admits to the skit being very funny, even as she takes pains to point out that she is, in real life, absolutely nothing like that."I tend to be rather sober," she says, with characteristic understatement, noting that her personality is in sharp contrast to the more jocular nature of her late husband, Marty (and even some of her seemingly staid colleagues). Despite her biting legal writing, she comes across, on camera, as unfailingly mild-mannered, decorous and polite, especially when the film explores her rather unlikely friendship, based on a shared love of opera, with her late conservative colleague Antonin Scalia.Rather than focusing on personality, however, the bulk of "RBG" has to do with its subject’s lifelong fight against gender discrimination - a fight pressed over many years, many cases and, in most instances, delivering only incremental change. One of Ginsburg’s early milestones as a litigator was a 1973 appearance before the Supreme Court in which Ginsburg argued, ironically, not on behalf of a woman, but a man: Air Force Lieutenant Sharron Frontiero had sought the same spousal benefits - for her husband - as a male servicemember would get. By striking this strategic blow for men’s rights, Ginsburg helped push the door open, if only a crack, to gender-blind policies that would ultimately get women one step closer to a level playing field."RBG" shines a strong, clear spotlight on a female jurist who are out to change the world, one small step at a time.