HERE'S an experiment get two cars, drive one to a wealthy area and the other to a less well off area. Leave each on the side of the road with the number plates missing and the bonnet open. Which one will attract the attention of thieves and vandals first?

A psychologist in the US conducted the experiment more than 15 years ago. He, one car in the Bronx, New York. Within 10 minutes of being parked the radiator battery were gone. Within hours almost everything had been removed. Then car began to be vandalised windows smashed, parts off, upholstery ripped.

The second car was parked the more staid surroundings Palo Alto, California. It sat touched for more than a week.

Then the psychologist smashed part of it with sledgehammer and continued his vigil. Within a few vandals had turned the car up side down and destroyed it.

His message was simple the breakdown of order could occur anywhere. In the Bronx it happened quickly the lack of number plates and the open bonnet were enough to signal the car was "fair game". In Palo Alto a further signal was needed, which the sledge hammer provided. But then, just as in the Bronx, respect for the car as private property was gone. People seemed to believe that if they took what they wanted no one would care.

The "broken windows" theory of policing was proffered by two academics in a 1982 edition of the US magazine Atlantic Monthly, referring to the car experiment.

They said that if a window in a building is broken and left Unrepaired, before long all the windows in that building will be broken, no matter what sort of area it is in. If the window is repaired, however, the other windows should be left intact.

The theory was one of those promoted and acted on by New York's former police commissioner, William Bratton, when he came to the job in 1994.

Bratton, who takes credit for reducing the level of crime in the city by 27 per cent over the last two years, took the "broken windows" view that unimpeded small crimes create an environment where more serious crimes are more likely to take place, because criminals see the lesser offences being ignored and believe they have the freedom for more serious acts.

Tackling the lesser offences had four major benefits, according to Bratton.

1. The public appreciated the effort.

2. Some of those arrested were found to be the subject of warrants for more serious war crimes.

3. Questioning those arrested brought an increase in the amount of information gathered by the police on crime generally.

4. Many minor criminals took to leaving their handguns at home in the past they knew their street offences would not attract police attention, now they feared being searched and found with an illegal weapon.

The last item is supported by an analysis of the declining murder rate in New York in recent years, carried out by the John Jay College of Criminal Justice. The murder rate in the city fell dramatically, from about 2,200 in 1990 to about 1,500 in 1994 and 1,200 in 1995. Not only that, but the number of people killed from gunfire was down, too, from 76-77 per cent to 72 per cent.

One conclusion is that, because of the way the police were acting, people with illegal guns were more likely to leave them at home. If a row developed on the street, it was less likely to end with someone getting shot.

It has been argued that Bratton had a number of advantages when he took charge at the NYPD, not least the fact that the police force had grown he was the first Commissioner with 38,000 officers at his disposal.

But at least part of the fall in "crime" must be due to the "assertive" policing methods' adopted in relation to lesser, ore "quality of life", offences.

There is another side to assertive" policing. Its critics call it "aggressive" policing and point to a rise in complaints against the police since it started.

Bratton was asked last year what he thought about the fact that complaints about police behaviour were up 25 per cent. He said there was a need for officers to be better trained and supervised.

But he called for some "perspective" to be applied his 38,000 officers were making more than 300,000 arrests a year and generating only 5,000 complaints, he said, of which only a small proportion were substantiated. Against this there were 77,000 fewer victims of crime annually. "Let's balance it," he said.

Are there lessons for the Republic in all of this?

A few years ago comparing crime in this State to crime in New York once renowned as the world's most violent city might have seemed pointless.

But as the Republic has seen an increased use of violence by thieves, the growth of drugs and drug related crime, and the emergence of "contract killings", comparisons may be more valid now.

There were more than 101,000 serious crimes in the State in 1994, the highest level since 1983. Crime in the Republic rose 16 per cent in five years. Vigilante groups have emerged in some parts of Dublin, in addition to parents groups which say they now feel obliged to police their own neighbourhoods.

Against this the Garda can point to a higher detection rate and a 3 per cent fall in crime since last summer. The Garda also faces a number of disadvantages compared to the NYPD.

For example, unlike the NYPD they have to cope with a private army within the State the IRA which is well armed, subversive by design and members of which are not afraid to kill gardai.

Over the last three years the NYPD has also enjoyed a great deal of political support for its initiatives, and increased resources when needed. In this State the Garda faces disadvantages created by Government priorities.

Garda representatives of most all ranks say the force is being "run down" because recruitment has not kept pace with retirements (the Government rejects this argument, saying Garda numbers are down because more civilians are being used to do clerical work previously done by gardai).

The Garda is now relatively small compared to the NYPD there is a garda for every Irish citizens, compared to an NYPD officer for every 236 citizens in New York. And in New York, criminals are more to likely to serve their prison sentences, compared to the Republic where large numbers of prisoners are let out early due to lack, of space.

The NYPD got its first helicopter in the 1940s and now operates eight. The Garda has only just been promised its first helicopter, and still has to use Army pilots.

Last week a Dublin TD hailed the "intensive policing" of one small area of his constituency, consisting mainly of two blocks of flats where criminals seemed to have taken over.

Extra gardai were assigned, and for a while the area was transformed. But then, for reasons apparently related to Garda resources, the gardai had to be moved. "The criminals were watching, and they were back in like a shot," he says. Now the area is as bad as ever.

By the middle of next month the Government must decide on a replacement for Mr Patrick Culligan, the Garda Commissioner, who is retiring. The new Commissioner will do well to make the sort of impact that Bratton made in New York in the war against criminals. But it may be that his most important battles will be with the Government.