Proponents hope the cameras will reduce the number of citizen complaints and costly lawsuits over police misconduct while at the same time discouraging citizens from making baseless accusations. The U.S. Justice Department has warned of the scarcity of research on the cameras' effectiveness, but a widely cited study of body cameras in 2012 by police in Rialto, Calif., a small town about 55 miles east of Los Angeles, found that complaints against its officers plummeted by 88 percent that year while officers' use of force dropped by 60 percent.