The Diallo case is a mirror image of the last celebrated police case, the trial of four Brooklyn officers in the brutalization of Abner Louima. In Brooklyn, enraged officers systematically raped and beat Louima, a suspect in their custody, and their precinct tried to cover it up.

But in the Diallo case, there was no sadism, no rage, no coverup. Instead, there was just standard operating procedure: plainclothes officers accosting a civilian who might well have mistaken them for gangbangers, firing their guns in confusion and fear at the first mistaken hint that he might be armed, hitting Diallo 19 times.

Around the country, it is not rogue officers but standard operating procedure which has turned police brutality into the civil rights issue of the decade. In that sense, Diallo’s case, not Louima’s, goes to the heart of the matter.

Studies by the U.S. Justice Department and the University of North Carolina have documented that fatal police encounters are likely to begin not with major crime but with a citizen’s casual defiance of an officer on a minor public-order matter. Take, for instance, a traffic stop, which led to the asphyxiation death of Johnny Gammage while in police custody in Pittsburgh in 1995, a case which brought the Justice Department into its most sweeping police-brutality investigation; or intoxication, the condition in which Archie Elliot of Prince George’s County, Maryland was shot 14 times in the back the same year.

Behind the standard operating procedures — and behind these deaths — is a profound debate over policing philosophy.

The plainclothes neighborhood-sweeping squad known as the Street Crimes Unit, to which Boss, Carroll, McMellon and Murphy were assigned, was established as a vehicle for Giuliani’s crime-reduction strategy — a strategy he claims is responsible for a reduction in crime so drastic that the city is now among the safest in the U.S. After being elected in November 1993, Giuliani and his new police chief William Bratton declared that no offence was too small — not begging in doorways, single-joint marijuana sales in public parks, squeegee hustles in traffic — and no offender too low-level to escape police attention.

More than a strategy, their approach has become a law-enforcement faith, variously known as zero-tolerance policing, broken-windows policing, or quality-of-life policing (depending on whether the speaker wants to appear tough, intellectual or socially concerned). It is emulated by police departments from New Orleans to London.

Diallo’s death is the dark side of the zero-tolerance movement — as are New York City’s soaring numbers of police brutality complaints and $25 million annually in out-of-court settlements in brutality cases.

In his press conference after the Diallo verdict, Giuliani inveighed against those who hold “different standards for cops.” Yet for months New York’s Civilian Complaint Review Board has been at odds with the NYPD over the small number of legitimate complaints which even rise to disciplinary hearings. It is still the NYPD, not the critics of brutality, which evades an even standard for officers’ behavior.

It’s not too much to say that Diallo’s death can be traced back to the founding document of the zero-tolerance faith, its Sermon on the Mount: a 1982 article in the Atlantic Monthly entitled “The Police and Neighborhood Safety,” written by James Q Wilson, a conservative political scientist, and George Kelling, a criminologist who had studied foot patrols in Newark.

Wilson and Kelling’s central argument was simple, centered on what they called their “broken windows” hypothesis. If a factory or office window is left broken, passers-by will conclude that no-one cares, no-one is in charge — and will soon shatter the other windows as well. Soon that decay will extend to the surrounding street, which will become menacing and hostile. Said Wilson and Kelling, it is the small, seemingly insignificant signs of disorder — graffiti, loitering by the homeless, subway fare-jumping by teenagers — which lay the groundwork for more serious street crime and social decay.

The graffiti artists and fare-jumpers themselves, getting the message that social norms will not be enforced, become likely candidates for more dangerous lawbreaking; while citizens, feeling threatened by homeless beggars and squeegee-men, withdraw from the civic arena. So police, Wilson and Kelling argued, should go back into the business of aggressive order maintenance.

With its vivid central image and its implied rejection of economic or social explanations of crime, the broken windows hypothesis proved instantly appealing to policitians like Giuilani. And it is grounded in a sensible core perception: an environment of physical safety is one important element of any civil society. Few urban dwellers have not raged against the absentee landlord down the block whose crumbling tenement shelters crack dealers in the cellar. Few have not felt some relief when a police officer quietly intervened with a deranged, intoxicated stranger.

The only problem is that on the New York streets, “order maintainence” quickly became a synonym for brutal neighborhood sweeps and generous employment of the truncheon. One of New York City’s first broken-windows success stories, for instance, the cleanup of streets around Grand Central Station, was soon discredited after large-scale beatings of the area’s homeless by a privately-employed goon squad were exposed by the press.

And as the huge gulfs in political perception opened by the Diallo case show, such zero-tolerance strategies brought another unintended consequence: vast erosion of police legitimacy. “The larger concern about zero tolerance,” warned a 1998 study commissioned by the decidedly law-and-order US Congress, “is its long-term effect on people arrested for minor offenses … The effects of an arrest experience over a minor offense may permanently lower police legitimacy, both for the arrested person and their social network of family and friends.”

Indeed, Giuliani himself gave a backhanded acknowlegement of such consequences in his press conference Friday night: “We have already had a great deal of examination regarding police procedures” as a result of Diallo’s shooting: “Relationships with communities. Reaching out to communities. Dealing with people in a more respectful way.”

Neither Guiliani’s assurances, nor the acquittal of the four officers, are likely to bridge the zero-tolerance divide which Diallo’s shooting has turned into a political chasm in New York.

On the law, the jury had it right: Those officers did not set out to kill an unarmed immigrant on the streets. But as a political matter, Al Sharpton, for all of his notorious theatricality, made the case in plain and simple language Friday night. “Any man has the right to expect the police are protecting him, not shooting at him.” The Diallo criminal trial is over, but the Diallo case will haunt the politics of zero-tolerance policing for a long time to come.