General deterrence vs. specific deterrence

It is generally accepted that traffic law enforcement influences driving behaviour through two processes: general deterrence and specific deterrence [71][44]. General deterrence can be defined as the impact of the threat of legal punishment on the public at large. Specific deterrence can be seen as the impact of the actual legal punishment on those who are apprehended. Thus, general deterrence results from the perception of the public that traffic laws are enforced and that there is a risk of detection and punishment when traffic laws are violated. Specific deterrence results from actual experiences with detection, prosecution, and punishment of offenders.

The general assumption underlying police enforcement is that it should primarily aim at general deterrence, which is first and foremost achieved by increasing the subjective risk of apprehension. The subjective risk of apprehension, and hence the effectiveness of police enforcement, is larger if police enforcement is [26]:

Accompanied by publicity
Unpredictable and difficult to avoid
A mix of highly visible and less visible activities
Primarily focused on times and locations with high violation (maximum feedback to potential offenders)
Continued over a longer period of time

These general principles may need further region-specific tailoring to account for regional differences with regard to violation levels, road network status, and sometimes even social norms. Research has shown regional differences in the effectiveness of police enforcement [32][70].