As law enforcement’s use of body-worn cameras and dash cams has increased in the U.S., the growth of attorneys’ introduction of video evidence in court, including jury trials, has followed.

Psychology and criminal justice researchers are now trying to determine the various influences of this footage, such as its impact on trial outcomes.

One such study, which is published in the journal Behavioral Sciences and the Law, suggests both eyewitness race and available body-worn camera footage influence jurors’ judgments.

To examine the matter, researchers at the University of Illinois at Chicago and Lakehead University ran a “mock trial” study using evidence from an actual case where an officer used controversial force in an altercation with a Black motorist who was charged with resisting arrest.

“High-profile police-involved deaths of African American citizens have fueled public interest in police accountability and body-worn cameras,” said Bette L. Bottoms, UIC professor of psychology and co-author of the study.

Over 250 people participated as jurors, who were divided into three groups that either saw the actual body-worn camera video, which showed the officer becoming angry and agitated; read a transcript of the video, which included all statements and actions, but could not portray the officer’s emotion like the video; or were given the same facts without any mention of body-worn camera footage.

Jurors who saw footage of the arrest, compared with those who read a transcript or were not aware an arrest video was available, were less likely to vote the defendant guilty of resisting arrest, and also rated the officer’s use of force less justifiable, and the officer more culpable and less credible.

Witnessing on video the officer’s escalating emotions and the defendant’s reactions to being tasered appear to have made the jurors question the officer’s credibility and whether his use of force was justifiable, according to the researchers.

Further, when an eyewitness supporting the defendant was White, compared with Black, mock jurors were more likely to believe the defendant, less likely to consider the defendant guilty of resisting arrest, and more likely to consider the officer culpable for the incident.

“This is one more of many reasons to recommend police training that emphasizes remaining calm and professional in body language, voice and action,” Bottoms said. “Also, even though previous research has found African American defendants and victims are often believed to be less credible than others, now we have evidence that Black supporting eyewitnesses are considered less believable as well, highlighting the need for courtroom interventions that address bias.”