How does a sitting Supreme Court justice in her 80s suddenly become the subject of an Internet meme whose popularity has skyrocketed with the youngest generations?

Although documentary makers Betsy West and Julie Cohen lead into the life of Ruth Bader Ginsburg with her seemingly incongruous online fame, they quickly cut to the substance of Ginsburg’s significant contributions to the law over the decades to make the case that her authenticity has earned her the pop culture heat she currently enjoys.

Part of Ginsburg’s appeal surely lies in the almost comic study in contrasts she presents, as a small, soft-spoken, elderly woman with owlishly outsized glasses, whose legal arguments and Supreme Court opinions nonetheless reveal a strident and (pardon the pun) ruthlessly pragmatic approach to building a foundation for equal rights for women by setting one precedent after another, court case by court case, brick by brick.

As we see in the film, it’s this deceptively demure tenacity that’s earned Ginsburg, even as a liberal jurist, the open admiration of not only Republican U.S. Sen. Orrin Hatch, R-Utah, who suggested her appointment to the highest court in the land to then-President Bill Clinton, but also the genuine friendship of her fellow Supreme Court justice, the deeply conservative (and since departed) Antonin Scalia.

As with her husband, Marty, remembered after his passing as a clever, charming and progressively ahead-of-his-era spouse who willingly put second his own legal career to support hers, it would seem the men who get to know Ginsburg can’t help but be won over by her formidable intelligence and well-constructed logic.

For all of the “Saturday Night Live” skits and amusing Tumblr posts getting showcased to demonstrate Ginsburg’s avid fandom, West and Cohen understood the heart of “RBG” as a biography would have to be the words of Ginsburg herself, in the equal rights cases she litigated before almost all-male panels of judges, and in the opinions (and increasingly, the stern and disappointed dissents) she’s written from the bench of the Supreme Court.

Audio recordings of an even-tempered older woman addressing the finer points of the law in court do not naturally lend themselves to a thrilling cinematic experience, but by interspersing those quotes with the frank commentary of Ginsburg’s peers and contemporaries for context, “RBG” seeks to make a star out of the laws themselves, which represents a refreshing change of pace from the personality-driven politics of today.

The one time we see a crack in the genteel code of conduct Ginsburg’s mother drilled into her is when the film addresses Ginsburg’s off-the-cuff comments about then-presidential nominee Donald Trump. Ginsburg herself not only agrees with her critics that she should have held her tongue but also chides herself for her fears of going backward by reflecting on how much progress has already been made since the days when she and other women who studied law were accused of stealing jobs from more-deserving men.

This film makes no pretense about how flattering and sympathetic its makers are toward its subject, with an entire sequence devoted to profiling Ginsburg’s admittedly impressive workout regimen.

We watch Ginsburg giggle with glee (her adult children describe laughter as a rare thing for their mom) at Kate McKinnon’s posturing, swaggering impression of her on “SNL,” but when asked how much of herself she sees in this caricature, Ginsburg immediately said, “Not a bit of it.”

At the same time, when asked how she feels about her Internet-coined title of “Notorious RBG,” a nod to the deceased rapper Notorious B.I.G., Ginsburg notes that she and the artist have at least one thing in common, since they’re “both from Brooklyn.”

Quoth Chris Evans as Captain America: “I’m just a kid from Brooklyn.”

As superhero lines go, it’s not bad.