Crime is a Bad Thing. So is punishment. Right now, the United States has too much of both.
One factor that leads people to break laws (or violate other rules where violation risks a sanction) is that they’re likely to get away with it. Given many violations and a limited capacity to sanction, the risk of being punished may be small. And once potential violators know that, the number of violations rises further, further reducing the risk of being punished for those who do violate, in a vicious circle.
But the circle can go the other way around. Increasing the number of sanctions in the face of any given violation rate will increase the risk of sanction for each violator. Some of them — the ones for whom violating was only marginally better than complying at the previous sanctions risk — will then go back to compliance, which further increases the risk for all the remaining violators, and so on.
So high violation rate/low punishment risk and low violation rate/high punishment risk may both be stable equilibria: the dynamics of crime and punishment — of deterrence — are a case where positive feedback can lead to “tipping” phenomena.
If you’re in charge of handing out the punishments in a situation at the high-violation-rate/low-punishment-risk equilibrium, and your goal is to reduce the violation rate, what can you do? If you could borrow some spare sanctions capacity for a while, you might be able to force the rate of violations down to a level where you no longer need the extra capacity to keep the situation under control.
But if you can’t do that — if no temporary surge capacity is available — perhaps you can get the same result by concentrating your threats, rather than allocating them at random among the violators. Pick out a number of potential offenders equal to the number of sanctions you have available, and tell them that they’re now in the zero-tolerance group: every violation by any one of them will be punished. You have enough capacity to carry out that threat, even if all of them violate.
Once they start to figure out that your threat was for real, they will reduce their offending activity. (That doesn’t require that they be perfectly rational, only that they dislike whatever you’re using as a sanction enough to want to avoid it.) As their violation rate falls, you will find yourself with more sanctions capacity than you need to punish violations within the zero-tolerance group, which allows you to increase the size of that group. Once the newly threatened people respond by reducing their violation rate, you can expand the group still further. And so on, until (ideally) the entire population of potential offenders is in the low-violation-rate/high-punishment-risk equilibrium.
The key is to establish and maintain the credibility of your deterrent threat. The more convincing the threat is, the less likely it is that you will have to carry it out. That’s the logic of “broken-windows” policing, of “coerced-abstinence” management of drug-involved offenders under community supervision, and of low-arrest crackdowns on open drug markets.
I’ll be giving talks on this theme at noon this Wednesday in Room 610T at John Jay College in New York (899 10th Avenue [@59th St.]) and again on Monday 12/18 at the Harvard Center for Risk Analysis. Both talks are open to the public, so come and heckle if you’re around.