"Policing the Police: The Impact of 'Pattern-Or-Practice' Investigations on Crime"

An interesting draft study by Harvard economics professors Tanaya Devi and Roland G. Fryer Jr.


Here's the abstract:

This paper provides the first empirical examination of the impact of federal and state "Pattern-or-Practice" investigations on crime and policing. For investigations that were not preceded by "viral" incidents of deadly force, investigations, on average, led to a statistically significant reduction in homicides and total crime.

In stark contrast, all investigations that were preceded by "viral" incidents of deadly force have led to a large and statistically significant increase in homicides and total crime. We estimate that these investigations caused almost 900 excess homicides and almost 34,000 excess felonies.

The leading hypothesis for why these investigations increase homicides and total crime is an abrupt change in the quantity of policing activity. In Chicago, the number of police-civilian interactions decreased by almost 90% in the month after the investigation was announced. In Riverside CA, interactions decreased 54%. In St. Louis, self-initiated police activities declined by 46%. Other theories we test such as changes in community trust or the aggressiveness of consent decrees associated with investigations—all contradict the data in important ways.

And the whole study is here. According to my brother Sasha, who teaches at Emory School of Law and who knows a lot about this sort of economic analysis generally, though doesn't specialize in policing:

I can't immediately see anything invalid about this sort of analysis. A few things to keep in mind, based on these guys' credentials: (1) Harvard applied micro econometricians are pretty serious, (2) NBER papers are pretty serious, and (3) their acknowledgments footnote cites a bunch of serious applied micro econometricians. More to the merits, their introductory section (pp. 2–7) seems pretty serious about looking into (and rejecting) alternative explanations for their findings.

In my view, the biggest challenge to this sort of analysis is that whether a police brutality video goes viral isn't exogenous. Maybe such videos are more likely to go viral (1) when the behavior in the video is more egregious, which is more likely in cities with exceptionally bad police-community relations; (2) when the cities have exceptionally bad police-community relations (regardless of whether the behavior in the video is more egregious); etc. If that's the case, then the mere release of the video can result in increased crime, because of rioting, because the community is less likely to cooperate with preventive police activity, because police departments change their behavior to avoid negative PR, etc.—and the investigation doesn't play an important role. The authors reject this explanation because they also look at other cities that had viral incidents but no investigations, but whether a city with a viral incident has an investigation also isn't exogenous. So their identification assumptions aren't airtight; it's not exactly a natural experiment.

That said, it's an interesting result that a bunch of hot econometricians thought was worthwhile.

I would naturally be glad to post links to serious substantive criticisms of the study as well (whether of the finding that some such investigations decrease homicide and other crime, the finding that other investigations increase homicide and other crime, or both findings).

NEXT: Rights and Wrongs of "Defunding the Police"

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  1. This is an excellent paper I’ve referenced repeatedly.

    1. The slightly larger context is just two days ago I saw a comment somewhere that police pulling back after previous viral incidents induced no increases in crime.

  2. Ironically through the riots alone the current Floyd/BLM meme already has a significant black death toll and far more will probably be killed in the fallout that will follow for years to come. All over someone who from all the currently available evidence probably died of a selfinflicted drug overdose.

    As I’ve said most people live in a fantasy parallel universe curated by the MSM.

    1. At least cop indifference to drug status, which is something other than race.

    2. “probably died of a selfinflicted drug overdose”

      A selfinflicted drug overdose caused blunt force trauma?

      1. There was no evidence of trauma to the neck in the autopsy or I missed reading it. You can’t usually say repeatedly I can’t breathe if you can’t actually breath. Its probably safe to say even if it did contribute to his death the cocktail in his system was the main cause and normal person who wasn’t high as a kite probably wouldn’t have died from it.

        1. It’s not even that — Fentanyl (particularly homemade) can cause hallucinations, Meth is notorious for that. Lord only knows what he saw in the back seat of that cruiser — and his refusal to get in there is what led to the neck hold.

          And Fentaynl above 7 ng/ml when mixed with other drugs can be fatal. Therapeutic dose is 1-3 ng/ml.

          George Floyd Autopsy:
          Blood drug and novel psychoactive substances screens:

          1: Fentanyl 11 ng/mL
          2: Norfentanyl 5.6 ng/mL
          3: 4-ANPP 0.65 ng/mL
          4: Methamphetamine 19 ng/mL
          5: 11-Hydroxy Delta-9 THC 1.2 ng/mL; Delta-9 Carboxy THC 42 ng/mL; Delta-9 THC 2.9 ng/mL

          1. Floyd truthers on the case!

            I look forwards to the video screenshots and the MS-paint circles.

            Did you hear that the officer who seemingly killed him is actually a crisis actor, better known as the Cash Cab guy?

  3. Interesting albeit intuitive given that “viral” suggests the kind of emotionally charged response which leads to mob behavior and other overreaction.

  4. Case in point, the NJ State Police shooting of Maurice Gordon.

    It was the fourth time cops had contact with him inside of 3 hours — the first two for a DMV in a travel lane (out of gas both times) and then for 101 MPH and then (10 minutes later) 110 MPH in what I believe is a 55 MPH zone. DMV again, he can’t get his car out of the high speed lane, so trooper calla a tow an tells him he will take him “anywhere he wants to go.”

    Gordon then attacks the trooper, who shoots him. This all on video.

    4th stop that night, 2nd in 10 minutes for 45-55 over, he should have been in handcuffs…..

  5. And what point exactly is this case in?

  6. “In Chicago, the number of police-civilian interactions decreased by almost 90% in the month after the investigation was announced. In Riverside CA, interactions decreased 54%. In St. Louis, self-initiated police activities declined by 46%.”

    Probably because the cops assume (not without some justification) that the investigation is expecting to find police misconduct, and so anything that can possibly be construed as misconduct, even if actually justified, is going to get them in trouble.

    1. Possibly, but as I recall at the time, there was some FU component to the pullback by police as well, we’ll learn ya by giving you what you want.

  7. Cops do the “blue flu” thing all the time whenever someone threatens to hold them to account.

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