Publication
Petersen, K., Koper, C.S., Taylor, B.G. et al. Less-Lethal Weapons and Civilian Injury in Police Use of Force Encounters: A Multi-agency Analysis. J Urban Health (2024). https://doi.org/10.1007/s11524-024-00940-1
What Was The Issue?
For all the headlines and heated debate regarding the police use of force, very little of this debate is informed by data. This study examines the injury rates associated with four types of less-lethal weapons (ECW [Taser], Chemical Agent, Impact Weapon, and Canine) using data from large departments across the country.
How Did They Look At It?
The authors received use-of-force data on 200 randomly selected use-of-force incidents occurring in 26 large agencies located in 14 states from 2015 to 2019. 3707 of these incidents involved less-lethal weapons. A number of these cases were missing some data and were omitted from the analysis. The primary sample, therefore, contained 2348 cases from 17 large agencies.
These incidents were then coded as not injured, injured but not hospitalized, or injured and hospitalized or killed. Three of the incidents involved civilians who died. The weapon type associated with the highest level of force used in the incident was also coded. Basic probabilities and advanced statistical modeling were reported.
What Did They Find?
About half of the use-of-force incidents resulted in civilian injury. About two-thirds of these were minor injuries. Two of the three deaths involved ECWs and one involved a canine. The chart below shows the unadjusted probability of injury by weapon type.
The advanced statistical modeling that controlled for officer, civilian, and situational characteristics did not reveal any particularly surprising findings. A canine being used had a much higher probability of resulting in injury or hospitalization. The use of chemical weapons was associated with less probability of being hospitalized. The civilian possessing a weapon was associated with about twice the probability of being injured. If the officer using the force was not on a patrol assignment, the citizen was about half as likely to be injured.
The authors also used advanced modeling to produce counterfactuals. Think of these as a “what if” way of thinking about what could have happened, but didn’t. If the officer had used a chemical weapon instead of a canine, what would have happened? That’s a counterfactual. These estimates again suggested that the use of canines is much more likely to result in injury or hospitalization than the other weapons. Other weapons tended to look more similar in their predicted injury patterns, but chemical agents were still associated with a reduced likelihood of hospitalization.
So What?
The authors note that this study is largely consistent with prior research findings. Chemical agents and ECWs pose the lowest risk of injury to civilians and canines the highest. They emphasize that chemical agents carry less risk of hospitalization or death than ECWs. The authors note a number of limitations for their study, such as their sample not being nationally representative and substantial differences in injury rates by agency. Additionally, when multiple forms of force were used in a single incident, they could not determine which specific form caused the injury. These limitations did not prevent them from making policy recommendations. For example, they recommend that chemical weapons should be considered a less severe use of force than ECWs and policies should maximize the use of chemical agents over other less lethal tools. They also recommended that policies should limit the use of canines.
My $.02
This seems to be a well-executed study given the data available, but I think it's time to move beyond this type of general research. As the authors noted, their findings are largely consistent with prior work. Studies like this can offer a broad understanding of which weapons are more likely to injure civilians. It's reasonable to suggest steering officers toward tools that pose a lower risk of injury, but in practice, officers are going to use the tools at their disposal when they believe the situation calls for it.
If we want to reduce harm, we can't just focus on the tools—we have to understand the context, the choices, and the moments that shape their use. In this study, about half of ECW deployments resulted in injury. That also means that in about half of the cases, there was no injury. Are there clear circumstances under which injuries are more likely during ECW use? Do the injuries and hospitalizations typically result from secondary effects—like a fleeing suspect falling and hitting their head after ECW deployment? If that's the case, then training and policy could be refined to reduce the likelihood of that specific situation. But this type of study simply can't answer those questions.
We now have a general picture of the risks associated with various less-lethal options. If our goal is to reduce injuries, future research needs to help us understand the specific conditions under which injuries are most likely to occur—so that training and policy can target those situations effectively.
Are there clear circumstances under which injuries are more likely during ECW use? Do the injuries and hospitalizations typically result from secondary effects—like a fleeing suspect falling and hitting their head after ECW deployment?
This was essentially my question. I am more interested in the instances that resulted in death. The ECW was involved, but I do not believe it was the cause of death. I agree this study is very broad and I think context matters. Information like this can be misconstrued to suggest that ECW's were the cause of death.