Ruth Bader Ginsberg (a.k.a. the Notorious RBG) broke through the glass ceiling before that term had even been coined. As a young mother, she was one of the first women to attend Harvard Law School (though she graduated from Columbia because sexism). As a law professor and litigator, she was a leader in striking down discriminatory laws, even though no firms would initially hire her due to her gender (a word she brought into use in the legal realm). And then she was the second woman appointed to the Supreme Court of the United States, where she remains at the age of 85, still fighting for a level playing field for women, minorities, and even, when necessary, middle-aged white men.

Why was it necessary for an equal rights lawyer to help middle-aged white men? Because that was the best chance to have the American courts actually enforce what seemed to be plainly written in the Fourteenth Amendment to the U.S. Constitution, namely that everyone should have equal protection under the law. Of course, prior to 1954 those nice-sounding words didn’t apply to black people, and prior to 1970 they also didn’t apply to women. We have Ruth Bader Ginsberg and her late husband, Martin Ginsberg, to thank for the latter, and on the Basis of Sex tells the story of how they won that fight.

On the Basis of Sex takes a few liberties with the facts, but does a commendable job of laying out the ground rules for the dispute, particularly in illustrating the power of the principle of stare decisis. That principle is the defining characteristic of the common law legal system, and it requires similar cases to have similar results. The effect of stare decisis is that precedent (i.e., previously decided cases) is the main source of law in the legal system used by most of Canada, and all of the U.S.A. and basically every country that was ever a British colony.

Accordingly, if the first U.S. equality case involving a women denies equality for women (which it did, in the late 19th century), then the starting point in every subsequent U.S. women’s equality case is that the woman should lose. Which is highly problematic if you actually stop and think about it. Common law is an adversarial system that is not built to take account of the larger picture. So it takes a visionary like RBG to unstick the system, by striking down outdated ideas and bad case law, by finding the perfect set of facts to use in her legal arguments. And what better case to take before a panel of white male judges than the sad tale of a white man denied a tax exemption available almost exclusively to women?

On the Basis of Sex is a better movie than it needs to be. Even this small portion of RBG’s career is compelling, and it’s only one item on the long list of her contributions to women’s equality and American society. But like RBG, On the Basis of Sex aims higher in telling its story. In addition to showing where our society has been, the film also shows how far we still have to go. For example, for every 1950s comment to RBG about how lucky she is to be married to a smart man, there are five similar comments made this decade to my brilliant wife, who I literally have never caught being wrong (to the point where I should know to stop trying to, if only I was as smart as her). On the Basis of Sex works both as a tribute to an icon and as a reminder that can’t come often enough: we need to aim higher to achieve equality, because as much progress has been made, there is much more work to do.