Posted by Jay Livingston
Arrest data for some crimes rise or fall with the amount of that crime. If you see arrests for homicide increasing, you can be fairly sure that homicide itself is on the increase. By contrast, an increase in arrests for prostitution is almost certainly the sign of a “crackdown.” A higher level official – the precinct commander, the police brass, maybe even the mayor – has told the cops on the street to arrest more hookers.
Neither of these explanations accounts for the trend in marijuana arrests in New York, particularly in the Bronx. On Sept. 19, 2011, Ray Kelly, the NYPD commissioner, issued an order that police should not arrest people for possession of small amounts of marijuana, the personal-use weed that cops found in stop-and-frisks.
The Guardian has published some graphs (here) showing the numbers of marijuana arrests in 2011 and in the previous three years. These usually decline in the fall – cooler weather, back-to-school – and the Kelly edict should have steepened the slope. But that’s not what happened.
(Click on the chart for a larger view.)
Keith Humphreys at The Reality-Based Community notes that marijuana arrests are often “substitute arrests.” Just as a substitute drug is what you use when you can’t get the drug you want, a substitute arrest is one cops make when they can’t arrest the person for the crime they’d like to bust him for. The cops might be doing whatever they can to punish someone witnesses might not want to testify against – a high-level drug dealer, a frequent wife-beater, or even a robber. Or the cops might be using stop-and-frisk marijuana arrests to get troublemakers off the street, at least temporarily, in order to maintain order. Or they may be using the arrest to assert their authority (or from the arrestees’ perspective, throwing their weight around by hassling kids).
“Substitution arrest” may be good explanation for why police bother to make these one-joint arrests. But it does not account for the increase in such arrests following an order from the top to stop doing it.
I’m puzzled.
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*The title of this post is derived from one of Robin Hanson’s favorite constructions I’ve used it before (here), and I’ll probably use it again.