Many of us have been caught by those increasingly ubiquitous red-light cameras. Police departments and local governments argue that these sorts of cameras improve safety and increase revenue. Studies are increasingly putting the lie to the safety claim, but nobody's disputing that these traffic enforcement mechanisms bring in revenue. The Wall Street Journal reported in March that

... a study in last month's Journal of Law and Economics concluded that, as many motorists have long suspected, "governments use traffic tickets as a means of generating revenue." The authors, Thomas Garrett of the St. Louis Fed and Gary Wagner of the University of Arkansas at Little Rock, studied 14 years of traffic-ticket data from 96 counties in North Carolina. They found that when local-government revenue declines, police issue more tickets in the following year. Officials at the North Carolina Association of Chiefs of Police didn't respond to requests for comment.

California state law prohibits compensation to operators of these red-light cameras based on the number of tickets issued. Localities have been side-stepping this law through "cost-neutrality" provisions, which allow the cities to pay the operators up to a certain monthly amount. After that cap is reached, the city keeps all the revenue beyond that point. The intent of the law is to remove an incentive to ticket as a means of increasing revenue to the private operators. There is now a second appellate court ruling that has struck down the red-light programs as illegal under the state law.