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By combating gender discrimination that was enshrined in American law, future Supreme Court Justice Ruth Bader Ginsburg helped expand the concept of “equal justice for all” to encompass a lot more of “all.” The accomplishments of RBG, as she has become known, are far more stirring and substantial than the film “On the Basis of Sex,” a formulaic biopic that covers 20 years of Ginsburg’s life.

Director Mimi Leder and screenwriter Daniel Stiepleman (Ginsburg’s nephew) squeeze every incident covered by the film into some familiar Hollywood template, simplifying and glamorizing all the way. This is a film for people who think the worst thing about “Kiki” Ginsburg, as her friends and family called her, is that she doesn’t look enough like a movie star.

Felicity Jones, right, as Ruth Bader Ginsburg, and Armie Hammer as her dreamboat and part-time-saint husband. (Jonathan Wenk/Focus Features)
Felicity Jones, right, as Ruth Bader Ginsburg, and Armie Hammer as her dreamboat and part-time-saint husband. (Jonathan Wenk/Focus Features)

The movie star who does play Kiki from 1956 to 1975 is the pretty and ever-plucky British actress Felicity Jones, whose Brooklyn accent can’t compete with the one mustered by D.C.-bred Justin Theroux, who brings some welcome roughness to the characterization of brusque and braying ACLU Legal Director Mel Wulf. But Jones’s principal co-star is that reigning smoothie of the silver screen, Armie Hammer, playing husband Marty Ginsburg as helpmate, dreamboat, part-time saint — and crackerjack tax attorney to boot.

The drama begins at Harvard Law School, whose crusty dean (Sam Waterston, as Kiki’s recurring nemesis) can barely abide women among his students. Upon graduating — not from Harvard, but Columbia, when Marty accepts a job with a New York firm — Kiki finds that no such firm will hire her. She settles for a professorship at Rutgers, where she’s still teaching when the movie boogies to 1970 on the beat of the Chambers Brothers’s “Time Has Come Today.”

In between, the Ginsburgs raise two kids, and Kiki nurses Marty through testicular cancer. When a doctor tells them that the survival rate is 5 percent, our heroine announces that she intends to spend the rest of her life with Marty. That settles that.

As a middle-aged law prof, Kiki is challenged by her teenage daughter (an engaging Cailee Spaeny) and her students to put her feminism into practice. It’s Marty who finds the perfect vehicle: a tax case about a caregiver who was denied a deduction available to others. Why is the case perfect? Because the plaintiff (Christian Mulkey) is a man, yet if he wins, the precedent will apply to women as well.

The preparation for court, which involves Wulf and weary feminist trailblazer Dorothy Kenyon (Kathy Bates), is the movie’s best part. But when the case goes to trial, the legal showdown is presented as if it’s the climax of a high school underdog sports flick. Kiki is overconfident, inexperienced and easily rattled. Can she lob the winning shot into the net before the buzzer sounds?

From left: Jones, Cailee Spaeny and Kathy Bates in “On the Basis of Sex,” which follows the future justice from 1956 to 1975. (Jonathan Wenk/Focus Features)
From left: Jones, Cailee Spaeny and Kathy Bates in “On the Basis of Sex,” which follows the future justice from 1956 to 1975. (Jonathan Wenk/Focus Features)

The movie’s central role was once intended for Natalie Portman, who probably would have been more believable. But the presence of Jones — whose credits include sojourns in the Star Wars, Marvel Comics and Dan Brown universes — has one interesting effect: It suggests that the film is best appreciated as the latest installment in a franchise.

While it’s not exactly a sequel to “RBG,” the hit documentary from earlier this year, the film does seem designed primarily for viewers who just can’t get enough Ruth Bader Ginsburg. Viewed through that lens, “On the Basis of Sex” sort of works. As filmmaking, it’s clunky, but as fan service, it’s more effective.

PG-13. Opens at area theaters on Christmas Day. Contains some strong language and suggestive content. 120 minutes.

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