By the time a movie star of verifiable acting ability has been around for a few decades, you start seeing interviews like the one, recently, in which George Clooney mentioned quitting acting at least until something like Paul Newman’s role in “The Verdict” comes along. That film has become an industry veteran touchstone. Legal dramas featuring a flawed but nobly wily protagonist: These are catnip for maturing male beauties eager to remind audiences they can A) carry a character-driven project, and B) quit coasting on their charm, or their ability to pretend to kill people, for a couple of hours.

In his 40s, Clooney took on such a role in writer-director Tony Gilroy’s “Michael Clayton.” Now, Denzel Washington has done the same, as the consciously unsmooth operator in nearly every shot of the flamboyant performance showcase “Roman J. Israel, Esq.,” written and directed by Dan Gilroy, Tony’s brother.

Gilroy wrote the part for Washington. A “bit of a savant” is how one character describes Roman’s personality and compulsive behavior. For 26 years, this brilliant but socially maladroit activist has worked in the LA law office of a well-known criminal defense attorney. His boss’s death pushes Roman into the public light, and it’s clear this throwback in the ill-fitting suit and retro Afro has no taste or tolerance for the grinding compromises of the criminal justice system.

In a condescending spirit of pity, Roman’s hired on by hotshot attorney George Pierce, played by Colin Farrell. The instigating conflict in “Roman J. Israel, Esq.” comes from Roman’s unsanctioned handling of a case involving a young man wrongly accused of murder. Without giving it away — there’s a genuinely effective twist involving the identity of a new client — Roman breaks the law, comes into some money and spends the rest of the film reckoning with that decision. We’re set up for all this in an early throwaway line of Roman’s, inspired by real-life Equal Justice Initiative founder Bryan Stevenson: “Each one of us is greater than the worst thing we’ve ever done.”

As a writer, Gilroy hits about .500 for individual scenes, a believable one followed by an artificial construct. Early on, Roman explains the “esquire” designation to signify a standing “slightly above ‘gentleman,’ below ‘knight.’” This is on-the-nose stuff. Roman meets a valiant civil rights activist, (Carmen Ejogo, of “Selma”), who invites him to a meeting of protesters, and it quickly goes south, with Roman getting upbraided by two young women for his old-school manners. It’s not a short scene, but it peaks just when it gets interesting. The movie lacks key progressions and transitions, especially in its middle section. “Roman J. Israel, Esq.” is a morality tale primarily about a good, sympathetic mess of a Don Quixote who screws up. Secondarily, it’s about the Farrell character’s change of heart, brought about by the idealist in his midst. The two men’s crisscrossing transformations never quite convince.

It’s frustrating, because the actors are all excellent and the movie’s actually trying to speak to the audience’s better instincts about what makes a grown-up movie protagonist worthwhile. Clearly with his star’s input, Gilroy invents a flurry of character tics and eccentricities. Still, you stick with it, or a lot of it. Even when the movie loses its way narratively, Washington’s in there, slugging, building a living, breathing character out of Gilroy’s knight-errant.

Michael Phillips is the

Chicago Tribune film critic.