The BBC's Peter Grant reports on a controversial policing policy

Detective Superintendent Ray Mallon, who is currently suspended as head of Middlesbrough CID, has been the most colourful advocate of this strategy in Britain.

In 1996 he famously promised to quit if he failed to cut crime on his patch by 20% in 18 months - gaining him the nickname 'Robocop'.

Although zero tolerance has wide political and popular support, it has far-from-universal support among many UK police forces.

It is also questionable as to whether it was this approach, or some other factor, which was responsible for the recent falls in crime in New York and elsewhere.

What is zero tolerance?

The precise origins of term are obscure, but it has become associated with policing techniques used most famously in New York City and other parts of North America.

In New York, police have used computers to anaylse crime hot spots street by street and crime by crime before introducing a zero tolerance approach.

It has been used in the UK in the King's Cross area of London, Hartlepool, Middlesbrough and Strathclyde.

The strategy is based on the 'Broken Windows' theory - first developed by two American academics, George Kelling and James Wilson, in 1983.

According to their theory, there is a link between disorder and crime - a view shared by Labour politicians. The thesis goes: visible signs of decay - litter, broken windows, graffiti, abandoned housing - signals public disinterest.

Fear of crime is greatest in these neighbourhoods, which prompts 'respectable' community members to leave.

This undermines the community's ability to maintain order and decline follows.

Reasoning that it is easier to prevent a neighbourhood's slide into crime than trying to rescue it, the theory demands that even minor misdemeanours must be pursued with the same vigour as serious crimes.

What are initial results?

Figures for New York have been well trumpeted. Since 1993, major crime in that city has fallen by 39% and murder has fallen by 49%.

In the UK, results have been similar. Det Supt Mallon managed to deliver on his promise to cut crime by 20% in 18 months - figures for the three months to February 1997 showed a 22% fall.

Det Supt Mallon also achieved these kinds of results in his previous job in Hartlepool where he oversaw a reduction in crime of 38% in 28 months.

Criticisms of zero tolerance