New Study: Do Body Cams Lose Their Behavioral Effect Over Time?

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You may recall the world’s first study of the effect of body-worn cameras on officers’ use of force and on citizens’ complaints against police.

Conducted with the Rialto (CA) PD and published in 2014, this benchmark research showed that during a year that some officers were equipped with body cams, use-of-force incidents dropped about 50% and complaints plunged more than 90%, compared to the year before. In a dozen other jurisdictions, subsequent experiments discovered virtually identical trends.

But, some observers wondered, would this dramatic impact last over time? Scientists are familiar with what’s called the “Fade-out Effect.” In some cases of experiments involving human behavior, initial outcomes tend to diminish after the test-focused “intervention” ends, and old patterns fall back into place.

Might this be the case with BWCs, as officers and the public alike become “desensitized” to the once-novel equipment?


As a rule, long-term follow-up is rare, but a team led by Dr. Alex Sutherland, a British criminologist, has looked at Rialto’s experience across a three-year period since the experimental 12 months ended.

Their conclusion:—spoiler alert!—yes, the positive impact of BWCs on force frequency and citizen complaints does endure.

In a paper recently published in the Journal of Criminal Justice, Sutherland summarized various charts tabulating bare numbers and rates per 1,000 arrests:

“[I]n the 12 months prior to the body-worn cameras experiment starting, both complaints and use of force were higher. During the experimental period, both fell (complaints almost to zero)…. What is clear and striking is that in the three years after the experiment finished, both complaints and use of force remained comparatively low,” even though the number of officers on the street in Rialto, a city of about 100,000 population, increased significantly. (All now wear BWCs.)


These findings of a “new normal,” Sutherland writes, “carry a clear policy implication” for departments. “The findings suggest that police officers do not become habituated to the effect of the body-worn cameras, and that persistence rather than fade-out effects may characterize this emerging technology.”

Sutherland’s paper, which includes an intriguing elaboration on the Fade-out Effect, is titled “Post-experimental follow-ups—Fade-out versus persistence effects: The Rialto police body-worn camera experiment four years on.” It can be accessed for a fee by clicking here. This will also take you to a free abstract.

“The final word on the impact of body cams is probably not yet in,” says Dr. Bill Lewinski, Executive Director of the Force Science Institute.

At about the same time Sutherland’s study was reported, results were issued showing a contrary outcome from research in Washington, D.C. A study there involving more than 2400 Washington Metro PD officers revealed “very small” effects in changing officer and civilian behavior, “none of which rose to statistical significance.” (This study, “Evaluating the Effects of Police Body-Worn Cameras,” can be accessed free of charge by clicking here.)

In contrast to that, an internal report recently released to the public from the San Diego PD showed “a significant drop in allegations against officers for both misconduct and overall use of force” across a three-year accounting.

Thus, the march toward “settled science” on this issue continues.
[For a detailed report on the original Rialto experience, see previous Force Science News article.]

Our thanks to Atty. Michael Brave, Director, CEW Legal for Axon Enterprise Inc., for alerting us to the Sutherland study.

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