Thread by @jonmummolo

My latest research out today in @PNASNews. “Militarization fails to enhance police safety or reduce crime but may harm police reputation.” (thread)

Article (open access): pnas.org/content/early/…

[Photo credit: Shutterstock/JPL Designs]

Four yrs ago this month, coverage of the heavily armed police response to protests in Ferguson, MO fueled a national debate re: police militarization. Police claim militarized units enhance public/officer safety. Critics claim they target racial minorities/erode trust in police.

I wanted to know who was right. But, as @radleybalko writes, “The biggest barrier to [analyzing police militarization] has always been that the data just don't exist.''

So, I FOIA’d hundreds of police agencies for records of their SWAT team deployments, eventually hitting pay dirt in Maryland. (Why Md.? It’s quite a yarn. See here: tinyurl.com/mpvada.) I also drew on existing administrative data sets and conducted survey experiments.

Data in this study:

-Records of all Md. SWAT deployments FY2010-2014 (~8200 deployments)

-Original national panel measuring SWAT team acquisition (~9000 agencies: 2000, 2004, 2008)

-Survey experiments, incl. oversample of African American respondents

Here's what I found...

Finding #1: SWAT teams mostly deployed for non-emergencies (service of search warrants). Property damage is common. Use of deadly force is rare.

Finding #2: SWAT teams deployed more often in areas with high % African American residents, *even after controlling for local crime rates and other area attributes*.

Finding #3: When an agency acquires a SWAT team, I find no detectable decreases in violent crimes or officer injuries/deaths, (within agencies over time).

Finding #4: Seeing militarized police in news reports--relative to images of traditionally equipped police--may harm police reputation (e.g., public less likely to support police funding or to want police in own neighborhood). Also some evidence for inflated perceptions of crime.

Finding #5: Surprisingly, these effects do not appear to vary with the race of survey respondents (though white respondents have more positive views of police at baseline).

Conclusion: claimed benefits of militarized policing---improved public and officer safety---are not, on average, supported by the data. Often-discussed trade-off between civil liberties and public safety appears in this case to be a false choice.

Policy implication: SWAT teams were created to handle violent emergencies like active shooter situations. Results suggest restricting their use to these emergencies rather than using them in routine police work may benefit both police and citizens, especially citizens of color.

Thanks @justingrimmer @AlexDBlackman CConrad @tedenamorado @andyguess JHainmueller @andrewbhall DKronick ALerman NMalhotra @mellosteve2 TMendelberg NMurukawa TMoe @petersonerikj JRodden @GarySegura MTomz @seanjwestwood @avitale @VeslaWeaver @drlaurenawright @xuyiqing for advice!