A grand jury had failed to indict a police officer who choked an unarmed black man, Eric Garner, to death. They had stopped him on the street for selling "loosies", single cigarettes. Protests against police killings that had been boiling away across the country – particularly in Ferguson, Missouri – spread into the five boroughs.

Then a black man claiming vengeance for police violence shot two cops dead in their squad car, execution style.  Struck with grief and fury many officers turned on the new mayor, Bill de Blasio, who they believed backed the protesters, who were now, more than ever, the enemy.

Men who should have known better, former mayor Rudi Giuliani among others, took to the air to add fuel to the fire, pointing fingers at de Blasio.

Then suddenly in the midst of all this, petty crime across New York appeared to simply stop.

In the week leading up to January 6, in a city of eight million people, police officers arrested or ticketed just 22 people for jumping the turnstile. In the same period a year ago, nearly 1400 fare-beaters were caught. Across the city only 347 criminal summonses were written during those seven days, compared with 4077 a year before. Clearly the scofflaws had not left town.

Rather police in America's largest city have quietly gone on strike.

Tension between police and minority groups is neither new nor unique to New York, but the current febrile state is worse than it has been for years.

It did not begin with Eric Garner's death either. In part it is bound up with the tough crime-fighting strategy known as Broken Windows policing.

In the 1980s and early 1990s New York was struck with violent crime as a crack epidemic swept across the nation. At the height of the violence in 1990 there were 2245 murders in the city.

That year a Bostonian called William Bratton was hired to head the New York City Transit Police. Bratton had served in the Military Police in Vietnam and climbed the ranks fast on his return. By the time he landed the job in NYC he had embraced the social scientist George Kelling as an intellectual mentor. Kelling was one of the co-authors of a paper that became the basis for Broken Windows policing.

The theory holds that crime spreads when social order is allowed to fray. In response authorities tackle petty crime. On the New York subway system Bratton cracked down on the fare evaders, graffiti artists, drinkers and the panhandlers that made the system a misery for other users.

His hard line attracted favourable attention and in 1994 Mayor Rudi Giuliani made him NYPD Commissioner. Together they prosecuted a "zero-tolerance" policy.

Skip forward a generation and crime in NY has plummeted. Last year there were just 332 murders.

In the intervening years Bratton had been poached to lead other police forces but his Broken Windows strategy remained in place, supported doggedly throughout Giuliani's term as mayor and then that of his successor, Michael Bloomberg. De Blasio has poached him back from Los Angeles.

While many in Manhattan celebrated the new life in the city, others, the targets of the policy, grew frustrated and hostile.

Broken Windows demands that crime managers track infractions and flood targeted areas with police, who in turn are encouraged to make their presence felt.

To that end the NYPD had adopted a tactic to match the strategy – Stop, Question and Frisk.

Under this tactic patrol officers stopped tens or even hundreds of people during a shift, whom they had "reasonable suspicion" might be about to commit a crime.

What constitutes "reasonable suspicion" is not clear.

By 2011 the policy was at its peak and 700,000 people were stopped and subjected to sometimes humiliating street searches. Between 2004 and 2012, police had stopped 4.4 million people, 87 per cent of them black or Hispanic.

Despite that "reasonable suspicion" the vast majority were innocent of any crime, and just 6 per cent of the searches led to arrests.

By then a protest movement against the Stop and Frisk policy had begun and concern about the NYPD's tactics had grown to the extent that a federal government monitor had been appointed to watch over the force.

Social scientists were beginning to question Broken Windows impact on crime. Some noted that the fall correlated with a 35 per cent drop in the city's unemployment rate. Others wondered if demographic changes were the cause, noting similar falls had been seen in other cities that did not practise Broken Windows.

In August 2013, a federal judge found Stop and Frisk to be unconstitutional. "No one should live in fear of being stopped whenever he leaves his home to go about the activities of daily life," Judge Shira A. Scheindlin wrote in her decision, noting that when minorities were stopped, they "were more likely to be subjected to the use of force than whites, despite the fact that whites are more likely to be found with weapons or contraband."

By then police tactics had become a political issue. After a generation of Republican rule in which police were used to the unquestioning support of law-and-order government, the Democratic Party's Bill de Blasio won office having campaigned on ending Stop and Frisk and repairing the relationship between minorities and police.

Worse, from the point of view of many on the force, and in particular from that of the police union, de Blasio backed laws against racial profiling and the creation of an inspector general to oversee the NYPD.

Police, and in particular Patrick Lynch, president of the Patrolman's Benevolent Association, were furious.

Cops, he said, need the unwavering support of the City Hall. Lynch encouraged his members to sign waivers that said,

"I, as a New York City police officer, request that Mayor Bill de Blasio and City Council Speaker Melissa Mark-Viverito refrain from attending my funeral services in the event that I am killed in the line of duty," they said.

"Due to Mayor de Blasio … consistent refusal to show police officers the support and respect they deserve, I believe that their attendance at the funeral of a fallen New York City police officer is an insult to that officer's memory and sacrifice."

When in December a grand jury decided not to indict the cop who choked Eric Garner to death, protests spread in New York. On December 4 the NYPD arrested more than 200 people, mostly on charges of disorderly conduct.

As the protests continued Lynch told his members to do their jobs "with extreme" discretion, claiming that police might not have the full support of the City Hall. Many interpreted this as an instruction to engage in work slowdowns.

Two days later, Ismaaiyl Abdullah Brinsley, a 28-year-old black man, shot and killed two on-duty NY police officers, Rafael Ramos and Wenjian Liu, as they sat in their car on a Brooklyn before fleeing into the subway and committing suicide. He had declared his intent earlier, writing on an Instagram account, "I'm putting wings on pigs today. They take 1 of ours, let's take 2 of theirs."

Hours earlier he had shot his ex-girlfriend.

In the end de Blasio attended the funerals, but as he spoke thousands of police officers turned their backs as they stood in ranks outside the funerals. They turned their backs too as he addressed a press conference in a hospital where the officers lay dead.

Lynch held his own press conference outside."There's blood on many hands tonight," he said. "That blood on the hands starts at City Hall in the Office of the Mayor."

It was around this time that the crime figures evaporated and a police force ostensibly wedded to proactive Broken Windows policing abandoned its city.

While sympathy for the murdered officers and their families is universal, many are now losing their patience with Lynch and the Benevolent Association.

"The implied threat to the city's elected leadership and electorate is clear: Cede leverage to the police in the course of negotiating labor agreements or risk an armed, organized army rebelling against civilian control," wrote The Atlantic in December. "Such tactics would infuriate the right if deployed by any bureaucracy save law enforcement opposing a left-of-centre mayor."

Many commentators have referred to a police "temper tantrum".

The New York Times railed in an editorial, "The problem is not that a two-week suspension of "broken windows" policing is going to unleash chaos in the city. The problem is that cops who refuse to do their jobs and revel in showing contempt to their civilian leaders are damaging the social order all by themselves."