Study
Engel and colleagues (2022a) used a stepped-wedge cluster randomized controlled trial to examine the effect of the Integrating Communications, Assessment, and Tactics (ICAT) De-Escalation Training on officer behavior (specifically, use of force) and officer and citizen injuries in Louisville, Kentucky, during January 1, 2018, to April 30, 2020.
The nine Louisville Metro Police Department patrol divisions, including eight geography-based divisions and one mobile unit operating across the city of Louisville, were grouped into three strata while ensuring equivalency of patrol officer counts and comparable preintervention crime and arrest rates. Then, each stratum was randomly selected for the discrete time points to receive the ICAT training. Officers in stratum 1 (Divisions 1, 6, and 8) were randomly selected to attend training from February 11 to May 17, 2019. Officers from stratum 2 (Divisions 4, 5, and 7) were trained from May 20 to August 23, 2019, and officers from stratum 3 (Divisions 2, 3, and 9) were trained from September 9 to November 21, 2019. The design allowed for a comparison between officers in the clusters receiving the intervention, and officers in the clusters experiencing “conditions as usual” who were waiting to cross over to the intervention group and receive the training. By the end of the study period, all clusters moved to the intervention group and received the ICAT training.
Use-of-force data were provided by the Louisville Metro Police Department. The department’s Standard Operating Procedure use-of-force policy delineated when and how force can be used by officers. According to the policy, commanding officers were required to complete an Administrative Incident Report for all reportable use-of-force incidents, which included all use-of-force incidents resulting in any injury, or the complaint of any injury, to either the officer or subject; or involving the use of physical force other than a control hold (a technique with a low probability of injury to the officer or subject that is employed to maintain physical control of a subject). The use-of-force outcome was measured as the number of individuals who had force used against them during a single encounter. This single encounter could include multiple police actions, given the escalating nature of force (i.e., an officer may initiate with a low level of force and increase) and the fact that multiple officers could use force against a single individual. The frequency of officer and citizen injuries reported as a result of use-of-force incidents was also examined. The Louisville Metro Police Department collected injury information for every individual and police officer involved in a use-of-force encounter regardless of the need for medical attention. The data provided did not include specific information regarding the type or severity of these injuries, only whether an injury was reported by the officer or citizen, and if it required medical attention. Counts of injuries included those reported by individuals or officers, regardless of whether medical attention was received.
The timeframe of January 1, 2018, to April 30, 2020, was used to examine changes in officer use of force and officer and citizen injuries as a result of the training. This period equated to between 14 and 20 months of observational data prior to the onset of training, and 8 to 12 months in the posttraining period for each division, depending on the timing of the training program for each division. During the baseline year (2018), force was used by 1,007 officers against 458 individuals, 80 officer injuries were reported, and 124 citizen injuries were reported.
Poisson regression with maximum likelihood estimation was used to examine the change in each outcome (counts of use of force, citizen injury, and officer injury) from the pretraining period to the post-training period for officers in divisions that received the training compared with officers in divisions that had not yet received the training. The model included individual and time-period (i.e., monthly and annual) fixed effects to account for time- and individual-invariant unobserved heterogeneity. No subgroup analysis was conducted.