The judges mulled the fact that private owners of red-light cameras were the ones who sent out tickets. The judges concluded: "Hang on, that's not legal."
Clearly, those weren't the literal words used in the judgment (PDF). The Fourth District Court of Appeals phrased it like this: "The City is not authorized to delegate police power by entering into a contract that allows a private vendor to screen data and decide whether a violation has occurred before sending that data to a traffic infraction enforcement officer to use as the basis for authorizing a citation."
The city in question is Hollywood, Fla. The court went further and said: "Dismissal of the citation is the appropriate remedy where a private third party effectively decides whether a traffic violation has occurred and a citation should be issued."
This particular case involved American Traffic Solutions. It bills itself as "the leading provider of traffic safety, mobility and compliance solutions for state and local governments, commercial fleets and rental car companies."
It also boasts "over 3,000 Road Safety Camera systems installed and operating throughout the United States and Canada."
The company subpoenaed Eric Arem in 2011. He fought and lost, but won on appeal.
I have contacted the city of Hollywood to ask whether it will fight the ruling or whether it will have all the tickets reissued by the police department. There is also the option, presumably, of refunding money illegally obtained.