“Many of his fellow officers considered him the most dangerous man alive – an honest cop.” That was the tagline for the rabble-rousing cop docudrama Serpico when it premiered 50 years and it’s astonishing, in retrospect, that Paramount Pictures slapped it on top of the poster and advertising, and that audiences turned out in large numbers to see it. The tagline accurately reflects the film’s central thesis: that institutional corruption is so pervasive in the New York police department – and, by implication, city departments across the country – that a cop interested in simply doing his job on the level would face impossible (and potentially fatal) obstacles. But to bring a sentiment like that into the mainstream feels impossible in the Hollywood of today, which would never risk alienating the Blue Lives Matter crowd. It surely helped that Al Pacino was at the height of his powers in 1973, the year between The Godfather and The Godfather Part II, and the start of a run that would continue after that, when he and his Serpico director, Sidney Lumet, would reunite for Dog Day Afternoon. As Frank Serpico, the real-life whistleblower who risked his neck to expose a crooked system, Pacino channels some of the toughness and audacity of Michael Corleone, but he’s much more vulnerable, with a shaggy, counterculture allure that’s not only his character’s undercover persona, but reasonably close to who he actually is. Patrolmen don’t typically show off their ballet moves in the office. Though Lumet would return to the police corruption beat with the two great 1980s docudramas Prince of the City and Q&A, he was a late hire for Serpico, which had started as a project for John G Avildsen – who’d made the disturbing Joe and would later direct Rocky – before Avildsen had a falling-out with cub producer Martin Bregman. (Bregman discovered Pacino in an off-Broadway play and the two would go on to make several more movies together, including Dog Day Afternoon, Scarface, Sea of Love and Carlito’s Way.) One of the great qualities of Serpico is that it feels like Lumet was brought in at the last minute and had to improvise his way through the shoot. It’s thrillingly spontaneous and rough-around-the-edges, with an instability that serves the material. In a bracing “how it started v how it’s going” juxtaposition, the film opens by cutting back and forth between Serpico’s swearing-in ceremony and him being rushed to the hospital with a gunshot wound to the face. From there, the rest of the film unfolds in flashback, as he starts his first day as a patrolman and doesn’t even get through his lunch order before discovering that graft is always on the menu for the police. His supervisor tells him that they eat for free at a local deli because the cops give the owner a break on double parking for deliveries. That may seem like an innocuous arrangement, but the slope gets slipperier from there. As Serpico attempts to work his way up to that shiny gold detective badge, he seeks to bridge the gap between the department and the communities it serves, starting with a plainclothes shabbiness that puts him at odds with his conservative, buzzcut peers. Shortly after landing with the bureau of criminal investigation (BCI), someone hands him an envelope with $300 in cash and the real trouble begins. He refuses to take what amounts to his cut of protection money flowing through the unit, but speaking out to his superior at any level, much less the press or outside agencies, would make him a pariah. He chooses the honest path and it nearly gets him killed. Working with the brilliant editor Dede Allen, who had cut The Hustler and Bonnie and Clyde, Lumet handles the passing of time in Serpico as a daring elliptical blur, with months and even years in his life going by in the space of a cut. One day, he’s buying a puppy for $5 outside his new garden apartment in Brooklyn and, seemingly in a blink, the animal is full-grown sheepdog. In the meantime, he goes to work every day and tries to make collars while persistently nagging his superiors to root out corrupt precincts or transfer him to a cleaner operation. After enough time has gone by, he and his lone ally Bob Blair (Tony Roberts) opt to go the press and see if the scandal can pressure the mayor to act. The courage of the real-life Frank Serpico did lead to the Knapp Commission in April 1970 and substantial house-cleaning in the NYPD, but the real achievement of the film is how sharply it articulates the impact institutional rot has on every cop in the department, even those who might have come to the job with a shred of Serpico’s idealism. Even when the hostility toward Serpico isn’t right out in the open, it can be felt every time he enters a precinct and his near-death is like a passive homicide attempt, with his supposed comrades deliberately exposing him to danger. Through Lumet’s typically superb location work, the streets of New York seem to reflect the carelessness of its guardianship, as the men responsible for cleaning it up are allowing the rot to fester. Released in the middle of an adventurous era in US film-making, Serpico did more than even The Godfather films in turning Pacino into the face of the rare moment when iconoclasm was a marquee quality. He could play the one honest guy in a roomful of men with guns and convince audiences to rethink their understanding of police work and appreciate the courage necessary to stand up for your convictions. The movie, like the life of its hero, remains a clear public good.