Hiring additional police can reduce Crime

Full report: The effect of police on crime and arrests: Are police deterring or incapacitating criminals? (PDF, 608.3 KB) 

Release date: 10.30AM, Thursday 11 April 2019

A new study by the NSW Bureau of Crime Statistics and Research (BOCSAR) has found that increasing police numbers can reduce crime, but not necessarily through the apprehension of more offenders. 

The BOCSAR study assessed the impact of additional police on rates of crime and arrests by exploiting a large increase in the size of the NSW Police Force in the lead up to the 2003 NSW State Election. Between 2002 and 2003 the size of the police force increased by 7.2%. This equates to an average increase of about 10 additional officers per Local Area Command.  

Because the increase in police numbers was, after controlling for a variety of other relevant factors, independent of crime, crime and arrest rates in the periods before and after the recruitment campaign could be compared. The analysis focused on offences known to be less susceptible to reporting and detection bias, namely murder, robbery, burglary, theft and car theft.  

The study found that a 1% increase in the size of the police force generated:

• a 0.8% reduction in theft;
• a 1.1% reduction in car theft;
• no convincing reductions in other crimes.

This roughly equates to one additional officer preventing 17 thefts and 4 car thefts each year.

The study also looked at how extra police reduce crime. The two possible mechanisms being:

1. additional police deter offenders from committing crimes or;
2. additional police arrest more offenders leading to incapacitation or cessation of offending among targeted offenders.

The study found no change in arrest rates following the increase in police numbers. This indicates that, in this case, police reduced theft and motor vehicle theft primarily through deterring offenders from committing crime rather than through incapacitation. 

Commenting on the study Acting Executive Director of BOCSAR, Jackie Fitzgerald, said it gives local support to overseas evidence that additional police reduce crime. Ms Fitzgerald cautioned, however, against assuming that these findings would generalise to present day NSW.  "The offending landscape in 2019 is very different to that of 15 years ago. For instance, innovation in security technology has made car theft substantially more difficult, irrespective of how many police are operating in NSW." 

Further enquiries: Jackie Fitzgerald 9231-9190, 0423139687

Copies of the report: www.bocsar.nsw.gov.au