The newcomers became targets of beatings and robberies, culminating in the burning of a Mexican-owned car by a group of Puerto Ricans. Reluctant to go to the police, a group of Mexicans – illegal immigrants who feared deportation – sought their own justice with plans to burn down a house belonging to Puerto Ricans.

Jose is Puerto Rican, but has gained the trust of the Mexican community by speaking with them in Spanish in the presence of a priest at the local church. He persuaded them to co-operate with police to find and arrest the perpetrators – thus avoiding an escalation of violence.

With a less empathetic police officer, this story might have had a different ending.

In one of the world’s most diverse cities, where nearly half of New York County’s residents are minorities, according to the 1999 US Census, officers are bound to come across situations like the one experienced by Jose.

In recognition of the role race and ethnicity plays in policework, Manhattan’s John Jay College of Criminal Justice offered to members of the New York Police Department a six-week course: Police Supervision in a Multiracial and Multicultural City. More than 500 officers enrolled in this summer’s pilot programme that will resume this autumn.

The interdisciplinary course draws on history and sociology, and focuses on themes that include “race and policing” and “myths and reality of crime”. A textbook is used, homework assigned and teachers lecture. But most importantly, teachers challenge the officers with questions they would not usually consider.

Richard Glover, who teaches in John Jay’s public management department, is one of the 28 teachers leading more than a dozen sections of the course. The seemingly simple question he asked officers one morning – “Should we ignore race?” – leads to heated discussion about how various races and ethnicities are stereotyped.

One officer discusses her experience patrolling the city’s Washington Heights area on night shifts, where she saw the neighbourhood’s predominantly Dominican population dealing in drugs or engaging in other criminal acts. “When I worked 4am to midnight, I thought all Dominicans were bad people,” she says frankly. “But when I worked the day shift I saw them going to work and church. I thought, ‘Oh my God, who are these people?’ ”

The students – many of African and Hispanic descent – listen attentively when Mr Glover says, “You cannot grow up in America without some concept of race. It is human nature to discriminate. We’re challenging you to recognise you have this tape running through your mind. In six weeks we can’t undo it. The best we can do is make you painfully aware of it.” Without this awareness, he emphasises, officers cannot provide impartial police service.

Impartiality is not commonly a word associated with police, especially in New York where the department’s reputation remains stained by notorious incidents of police brutality. Two cases are most vivid. In 1999, police shot 41 times at Amadou Diallo – an unarmed African street vendor – killing him on his doorstep. Abner Louima, a Haitian immigrant, was beaten by officers and sodomised with a broomstick in a police station bathroom in 1997. Last week, Mr Louima accepted a legal settlement of $8.75m from the city and its main police union.

Minorities represent about a third of the NYPD, according to 1999 figures. Yet accusations of racial profiling by police are rife. Even several minority officers in the class say it is not unusual for them to be stopped and questioned while off duty.

Peter Vallone, City Council speaker, played a major role in initiating the programme, which received $500,000 of funding this summer and will receive $1m in the autumn. It is perhaps no coincidence that Mr Vallone will be running for New York City mayor and that safety and policing top the agendas of all mayoral candidates.

“We’ve become such a race-conscious society, but we’re really not trained to be effective in dealing with those kinds of issues,” says Mr Glover. Police academy does provide some training in diversity, but there is nothing as focused as what John Jay College is offering.

Students say the class is giving them a chance to address a sensitive topic candidly and scrutinise themselves and how they regard others.

Jose Piedra, on the force for seven years, says he has a “different outlook now” because of the course, which has affected not only his police work but his personal life. “It’s something they should include in elementary schools.”

“This classroom is teaching me to do things in a different way,” said Genise Brown, who has been with the NYPD for 10 years. “People need to understand not just about the variety of people in this city. They need to learn more about the people they police.”