Still appears to be working

Here's an update to the police department's strategy to deal with chronic repeat suspended drivers by impounding more of their cars. We now have a fourth month of data, that the decline in suspended drivers compared to overall traffic tickets continues. The 218 suspended driving tickets in June represent 2.95% of the total tickets, which is the lowest month since the time-series comparison period starts in January, 2013. Each of the four months since the policy change has been the lowest month.

Now, a little theory: crackdown strategies like this are usually based on the belief that violators will be deterred. The deterrence can be specific (the offender ticketed is deterred from continuing to violate the law) or general (other suspended drivers, learning of the crackdown, will be less likely to drive and/or drive less frequently). Crackdowns are generally announced with considerable fanfare, in order to increase general deterrence.

There is a considerable body of research demonstrating that the deterrent impact of crackdowns usually decays rapidly over time. Interest fades, publicity lags, things rebound more or less to the same condition as before the crackdown. It will be very interesting to see if that occurs with the police impound strategy. It certainly hasn't yet, despite the fact that there has really been little publicity about the strategy since the initial blast of news stories back in February.

I think there is a good chance that the effect of this strategy may be quite sticky compared to other crackdowns, because this one is not just based on the deterrent effect. It has an additional component: removing the instrumentality of the crime--the car. Impounding the car for 30 days makes it more difficult for the suspended driver to continue to drive. The time and effort necessary for finding another vehicles to drive is significant, and that alone should impact the likelihood the driver gets back behind the wheel, as well as how quickly he or she does so.