Serpico is not a new kind of hero. The man who attempts to buck the system has been a source of fascination ever since the first Greek playwrights questioned the wit and wisdom of some of their gods. Serpico, however, is a new kind of cop film and its title character, beauti- fully played by Al Pacino, is a new kind of hero to meet pounding a beat. […] Serpico is obsessed with such things as honesty and integrity and compassion for the underdog to such an extent that when you leave the theater, your admi- ration for the man may be mixed with a certain amount of suspicion: he really is a driven figure, so neurotic that you begin to feel that his obsession has less to do with a sense of justice than with toilet training. This not to knock the man but to credit the complexity Lumet’s movie and Pacino’s performance, which are, after all, based on an authorized biogra- phy (written by Peter Maas), not always the most comprehensive source material. […] The French Connection tried to humanize cops by showing us that they had to be as cruel and ruthless as the people they were after, and recently we’ve been given films to demonstrate that good cops are hamstrung by the niceties of Constitutional freedoms, as Dirty Harry and Hit. Serpico does something else. It pres- ents its hero as a son of St. Francis of Copdom, an Establishment dropout who talks to the street people and listens to Bach, a mystic who wears love beads and sandals, who studies Spanish and takes ballet lessons. […] The American public is schizoid in such matters. We want heroes but we’re also frightened of them. It’s easier to feel comfortable with the kind of bunglers responsible for Watergate than it is with people whose moral codes are higher and more rigid than our own. […] There must be something wrong with anyone who professes piety. Serpico is about our world, not sim- ply its police corruption but its values, which have been so diluted that when we meet someone who acts on principle we know we’re in the presence of a freak. 

Vincent Canby, Serpico, the Saint Francis of Copdom, “New York Times”, 16 dicembre 1973