No evidence for Stop-and-frisk reducing crime

There's a long piece in the Washington Post (Wonkblog) today about claims that stop-and-risk reduce crime. I'm now becoming obsessed not with police brutality, per se, but with the discourse of police explanations. 

“No question about it, violent crime will go up,” New York police commissioner Ray Kelly declared on Meet the Press on Sunday, when asked if a recent ruling striking down the city’s “stop and frisk” policy would cost lives. “What we’re doing — and what we’re trying to do — is save lives,” he added on This Week.
Actually, there are some questions about it. The research is clear: Stop and frisk is applied racially unevenly. But there’s precious little evidence that it has worked to reduce crime. And then there’s the question of whether it could actually be undermining effective policing by alienating the very communities it’s meant to help.

What I like about the piece is the way the author then moves through social science research, the claims it makes, the claims it can make, and the limitations of available data. He concludes:

Ultimately, Weisburd argues that this is the kind of question that you need a true experiment to resolve. “Let’s say they did a randomized experiment, with 500 control blocks and 500 treatment blocks, where you measure the number of minorities who live on each block,” Weisburd says. “They would have answers to the questions being asked.” Until then, Kelly is operating on the basis of precious little evidence, and in the face of serious drawbacks to the approach he’s chosen.

Also this lead poisoning thing - that violent crime is down because we are not being poisoned by lead - seems to have legs.

Violence in America - A historical look

A friend and historian asked me, in the wake of yesterday's post, to think about the ways that compliance might track against overall reduction in crime in the last few decades. This is important. Ray Kelly defended stop and frisk by saying it's lowered crime rates. TASER notes the 110,000+ lives saved thanks to their products. These arguments are complicated - exactly how many people should TASER CEWs (conducted electrical weapons) save in order to justify each death? How much do we need crime to go down to justify racial profiling and the abandonment of our Fourth Amendment rights?

Two articles on crime over time caught my eye of late, both from Talking Points Memo.

The first, "Humility and History," makes the argument that it is very hard to track causality while living in a moment of change, but that this is part of the role of the history. It's a particularly good piece for people looking for ways that liberal learning matters.

Marshall, the writer, then follows up with "Was Lead the Killer?", which looks at the decline in lead poisoning and violent crime. He considers a number of possible reasons for the decline in crime, then concludes:

Lead on the other hand has two big evidentiary chains behind it. One is the abundant evidence that lead poisoning early causes decreased IQs, diminished impulse control and various sorts of sociopathic behavior. It seems to take the ‘natural’ aggressive impulses of young men and put them into overdrive. Second is the very granular correlation between rising and falling rates of lead poisoning and rates of violent crime - offset by about 23 years. This doesn’t seem to apply just broadly in the USA but in other countries and even state by state in the USA.

That’s serious evidentiary backing. And I’d call it a solid theory. I just don’t believe it’s case closed. I think we need more research and also we’ll need to see what happens over the next ten to twenty years. More candidly, I think there’s part of me - perhaps the historian part of me - that’s inherently resistant to such monocausal explanations. But that may be bias more than clear thinking.

So that’s where I come down on this. Lead’s the only theory with solid evidentiary backing. But I don’t think it’s case closed.

I really like the "inherently resistant to such monocausal explanations" phrase, as I think that's exactly how historians ought to operate - open to understanding causality, resistant to single explanations (see 10,000 pieces on the "Fall of Rome" for another good case).

To me, I'm increasingly convinced by the argument that police have always acted this way (the cult of compliance) but are now being recorded by camera-phones and car-cameras (which police shout NOT be able to turn off), so have to make up explanations for their brutality. Hence, we end up with "non-compliance" as the catch-all. I am also increasingly convince that there has been a fundamental shift in police culture, the "Rise of the Warrior Cop," in a society increasingly tolerant of violating civil liberties in the name of security. This places the change into the post-9/11 change in American culture.

I am aware that these two explanations may lightly contradict each other. At the moment, I'm comfortable with that.