Body-Worn Camera RCT — Washington DC

Summary

Body-worn cameras had been widely adopted based on small observational studies suggesting they reduced complaints and use of force. The DC experiment—the largest RCT ever conducted on cameras, pre-registered, published in PNAS—found null effects on every outcome measured. Cameras did not reduce use of force, citizen complaints, arrests, or assaults on officers. The finding created significant controversy because the observational literature had shown consistent positive effects. The likely explanation: body cameras change behavior when officers and citizens know they're on; in a city where cameras are ubiquitous and deployment is universal, the marginal effect disappears.

Research question

"Do body-worn cameras reduce use of force, complaints against officers, or improve other outcomes?"

Methodology

Result

Null

No significant effect on use of force, complaints, arrests, or assaults; null across all pre-registered outcomes

Evidence strength

Strong

Randomized controlled trial with large sample.

Replication status

Partially replicated