Find 'em, catch em', put 'em in prison: how to reduce the crime rate

During the 1990s the United States experienced a significant drop in the incidence of most categories of crime. The assault rate in America dropped by more than one-third, burglary rates more than halved, robberies fell by two-thirds and car theft fell by three-quarters.

In Australia, by contrast, burglary and car theft fell only marginally during the 1990s while assault and robbery rates went up. Indeed, the International Crime Victim Survey of 17 countries shows Australians are more at risk than the citizens of most other developed countries. Australia ranks second highest overall (behind England and Wales) on the rate of victimisation, and we score higher than any other country on so-called 'contact crimes' such as robbery and assault.

It would be useful to know how the US managed to reduce criminality during the 1990s.

Explaining crime rate variations

Many different factors have been identified as possible causes for the dramatic fall in the American crime rate. These include the strong economy, the ebbing of the crack-cocaine epidemic and the reduction in the number of young males in the population as the 1960s birth-bulge matured.

Some of these explanations are more convincing than others. It is difficult to see why the strong economy should have reduced crime, for example, when crime increased during other periods of rising prosperity in America (most notably the 1960s). Furthermore, Australia's economy grew even more strongly than America's during the past decade, but crime rates here did not fall.

What we are looking for, then, is something distinctive about America in the 1990s. Two policy changes in particular are worth investigating.

One was the move in New York City and a number of other major centres to what has been called 'Broken Windows' policing. This strategy called for increased police surveillance of behaviour in public places in order to lower the level of official tolerance of relatively minor infractions such as vandalism, vagrancy and graffiti. The theory of Broken Windows held that serious crimes thrive in areas where nobody seems to care about the little things. Thus, by taking action on the small incivilities, the bigger and more serious anti-social behaviours should decline as well.

Economic rationality and criminal behaviour

The other major policy change that occurred in America in the period under review was that more offenders ended up in prison. This policy, too, was driven by an academic theoretical literature, although in this case the theory was more economic than sociological.

In the 1960s, the Chicago economist Gary Becker suggested that crime, like any other 'business', involves a rational calculation by individuals of likely costs, benefits and risks flowing from a given course of action:

"When other variables are held constant, an increase in a person's probability of conviction or punishment if convicted would generally decrease, perhaps substantially, perhaps negligibly, the number of offenses he commits ... a person commits an offense if the expected utility to him exceeds the utility he could get by using his time and other resources at other activities."

Becker reasoned that we can reduce the rate of criminal behaviour by changing this calculus. This can be done by raising the likelihood that offenders will be caught (which means spending more resources on policing) and/or by increasing the severity of the punishment (for example, by spending more resources on imprisoning offenders who are caught and convicted). Becker suggested that the former strategy is generally more cost-effective than the latter, although the relative effectiveness of detection and punishment rates in deterring crime depends on the extent to which potential criminals are risk-averse (risk-avoiders will be deterred more by the prospect of getting caught, while risk-lovers will be deterred more by the prospect of severe punishment).

The economic theory of crime that has developed out of Becker's original paper recognises that different individuals break the law for different reasons, that not all law-breakers are rational utility maximisers, and that different offenders will weigh risks and benefits in different ways. Nevertheless, it claims that, at the margin, more individuals will be deterred from engaging in criminal behaviour if the chances of being apprehended and/or the severity of punishment are increased: 'We can reduce crime in our community by increasing the probabilities of capture and conviction and the severity of the penalties.'