A message to you Rudy

To many New Yorkers, the zero tolerance policy meant quality of life. But for a mainly white police force it became a racists' licence to kill. And now its author, Mayor Giuliani, is facing the backlash. By David Usborne

The past five years have been lonely for Robert Lederman, a New York street artist who specialises in Adolf Hitler caricatures of Mayor Rudolph Giuliani. Through all that time, Giuliani, a former prosecutor and a Republican, seemed invulnerable to all political torpedoes. Even Manhattan's powerful liberal establishment embraced him. He was, after all, the "quality-of-life" mayor; the tough-guy leader, who made "zero tolerance" fashionable and who oversaw a downturn in the city's rampant crime rates.

Why, then, the giddy smile on Lederman's face on this sunny Wednesday outside the State Supreme Court in the Bronx? Because, suddenly, this 30- year-old subversive, who has scraped a living from lampooning the Mayor since he took office in 1994, is in the company of friends - lots of them.

For the last five weeks, Lederman has been at the centre of headline- grabbing demonstrations against the Mayor and his police department. His mocking paintings have become the protesters' battle-banners. His art has been on front pages and TV news bulletins. And the demonstrations tell him something has changed: Giuliani, tipped to run next year for a US Senate seat, maybe against Hillary Rodham Clinton, is in trouble.

The deepening crisis, which is enflaming racial divisions in the city, began nearly two months ago on a dark evening not far from here in the Bronx. Four plain-clothes officers of the police department's vaunted Street Crimes Unit were on patrol looking for a serial rapist. They spotted a man they thought was suspiciously loitering in the entrance hall of an apartment house on Wheeler Avenue. Within moments, the four men found themselves emptying their pistols into the hall. Together, they unleashed a sustained fusillade of 41 bullets, of which 19 struck the man and killed him.

The incident in itself might not have been so remarkable. Shooting people is a hazard of any New York cop's job. But several details set it apart. The officers were all white and their target was black. Moreover, he had no record and, as it turned out, was unarmed. The officers seemingly opened fire when he reached into a pocket. But he was reaching, they belatedly discovered, not for a gun but for his wallet. The victim's name was Amadou Diallo, a 22-year-old immigrant from Guinea, who worked as a street peddler in Manhattan. And his death uncapped a volcano of resentment towards the police.

With his zero-tolerance doctrine, the Mayor has given the NYPD licence to abandon standards of decency and human rights. Worse, some argued, it has given succour to racism in the police. What has been remarkable about the daily protests has not been their size so much as the diversity of those participating. Among the more than a thousand who have been arrested (and swiftly released) for blocking the doors of police headquarters have been blacks, whites, gays, lesbians, Hollywood stars, US congressmen and Orthodox Jewish rabbis. The Reverend Jesse Jackson, former presidential candidate, was arrested, and so was a former chief of the police department. Ed Koch, a former mayor himself, submitted to the plastic handcuffs. So did David Dinkins, Mayor Giuliani's black predecessor and still much respected among blacks and liberals.

On this day in the Bronx, emotions are at a new pitch. Inside the courthouse, second-degree murder charges are being read to the four officers. The chants out here are thunderous. "No justice, no peace" ... "Arrest Giuliani."

Yards away, beyond two metal barriers, several hundred off-duty police officers bellow a different message: what happened on Wheeler Avenue, they cry, was not murder but a tragic accident. "We serve an ungrateful community", read a placard.

Lederman, who is white, pauses to ponder the impact of the case. "I think there has always been an undercurrent of resistance to Giuliani, but never one symbol strong enough to bring that out on to the streets." The Reverend Al Sharpton, who has often been dismissed as a polarising and inflammatory figure on the New York stage, has been a key figure in these demonstrations, and his activism in the Diallo furore has earned him unusual applause.

"Sharpton's genius has been in bringing together people from every race, economic group and religion and getting them to work together on this," says Lederman.

It would be ironic indeed if Giuliani, who until recently was even being suggested as a future presidential hope for the Republicans, becomes impaled on the issue that he has seized as his own: law enforcement. So successful have been Giuliani's policies of zero tolerance - murders in New York have fallen by 70 per cent since he took office - they have been espoused by police forces around the country. He has followed his philosophy resolutely, applying it not just to hard crime cases, but to the squeegee men lungeing at car windscreens (they are no more in New York), to jay-walkers, to drunk drivers and even to dog owners who violate city leash laws.

In the first few weeks of the crisis, Giuliani infuriated critics by steadfastly speaking up for the police force. He tried to meet with the Diallo family, only to be turned away. When he attended a memorial for the dead man, he was jeered. In recent days he has reached out to local black leaders, whom he had previously spurned.

The early evidence suggests that the mayor is in a political tailspin. Latest polls show his citywide approval rating plunging from 60 per cent six months ago to just 40 per cent. "The mayor of the city is going down on the issue," commented Marvyn Kornberg, a lawyer for the four accused officers. "And his enemies are not going to let up."

Giuliani is not helped by an unhappy confluence of events. Last week, the trial got underway in another case of alleged police brutality. Five officers are being tried for the beating and torturing in 1997 of a Haitian immigrant brought into a Brooklyn precinct station after a street brawl. Abner Louima was allegedly beaten by the four arresting officers in the squad car and, once inside the station, was sodomised by an officer with the wooden handle of a toilet plunger.

Just as in the Diallo case - though to a lesser degree - Louima came to symbolise racist brutality by the police. Worse, when the story first broke, claims surfaced that one of the two officers involved in the sodomy told Louima to brace because this was "Giuliani time". It has hardly mattered that no evidence has ever surfaced that those words were ever uttered.

In an effort to blunt the criticism, the Mayor last week ordered some changes in the Street Crimes Unit - changes that officers have privately deplored. Fifty of its number are to be replaced with officers from ethnic minorities and, from last Sunday, all its members now operate in uniform.

It is not difficult to test the depth of mistrust that exists between New York's "finest" (an epithet rarely heard these days) and the city's blacks and Hispanics. As random interviews in the Bronx this week bore out, almost every non-white young man has a personal tale of harassment at the hands of the police. Above all, officers are accused of abusing their rights to "stop-and-frisk" suspects, especially if they are not white.

For Angel Rosado, 23, from Puerto Rico, it was the night he was strolling to visit his mother who lives in a housing project. He says he was picked up for "trespassing", because he was in an area of heavy drug activity and fitted the profile of a trader. He was fined $190 in court. "You can be walking down a street, and if you fit the description, they'll lock you up," he says.

George Sims, 31, adds: "If you are a black young man, you are a marked man. I feel like a marked man. It's that crazy."

Sims recalls leaving a film set in Harlem last September - he had been working as a PA to the director Spike Lee. He had his walkie-talkie and headphones with him, but he was stopped by a squad car and roughly frisked for a weapon. The officers said that there had been a burglary in the area, and it was only when the victim arrived and could not identify him that the officers let him go. "It's the kind of crap we shouldn't have to put up with," he says.

The Louima trial is likely to extend into summer. A hearing for the four officers accused of killing Diallo has been set for 30 April. So far, tensions in the city have been contained and the demonstrations have been peaceful. What might happen if either of the trials ends in acquittal is anyone's guess, but Robert Lederman is unequivocal: "If that happens, there will be riots in the city."

If that happens, Giuliani's future looks less than secure. It even opens the possibility, previously thought remote, of a victory for Hillary Clinton at the Senate.