Multiple studies over many years have consistently shown these devices to increase accidents at intersections.
A University of South Florida College of Public Health study has determined that red light cameras actually increase the number and severity of crashes, and the main cause of these accidents are people slamming on their brakes to avoid going through a yellow light, for fear of the red-light camera catching them. Other studies have shown that the reduction of side-angle collisions at intersections has been largely offset by an increase in rear-end collisions.
At some intersections where red-light cameras have been installed, it has been determined that the duration of the yellow signal was illegally shortened, thereby ensuring that there would be more violations and thus, more revenue. In the Tennessee case, 176 tickets ($8800 in fines) were refunded to drivers caught in the first 0.9 seconds after the signal turned red when it was discovered that the length of the yellow signal timing had been reduced by that amount.
In some areas, red light enforcement cameras are installed and maintained by private firms such as Affiliated Computer Services. In many cases, these private firms also administer the processing of citations. Many people disagree with this privatization of a police function.
In Texas, red light violators caught by a red light camera are served with a civil citation rather than a criminal citation. The civil infraction (civil fine of $75, no traffic points) conflicts with the same criminal infraction (fines of $1 to $200, and traffic points).