The Tennessee General Assembly is free to impose limitations on the use of automated ticketing machines, according to an opinion issued Monday by Attorney General Robert E. Cooper Jr. Cities and photo enforcement companies had complained that the legislature had "impaired contracts" when it enacted a law in July prohibiting the issuance of photo tickets to drivers making slow right turns on red. Right-turn citations have become the primary moneymaker for red light camera systems nationwide.

"Prior to the passage of Public Chapter 425, several local governments executed contracts with vendors to install and maintain traffic enforcement camera systems to assist the local governments in the issuance of traffic citations," Cooper wrote. "The local governments under these contracts would pay a certain percentage of revenues from all traffic citations issued by the traffic enforcement camera system. Per the opinion request, there was an understanding that a minimum number of traffic citations would be based on right-turn-on-red violations."

Lawmakers had spent months debating legislative limitations on red light camera systems, and municipal lobbyists believed they had beaten back any provisions that would have meaningfully changed existing practice. They were surprised when the final bill contained the prohibition on right-turn tickets and have hoped it would be struck down as a violation of the Constitution's contract clause. Cooper does not think that will happen.

"This office finds compelling arguments exist to support the position that the passage of Chapter 425 does not unlawfully impair any contractual relationship," Cooper wrote. "While Chapter 425 might arguably diminish the income received under a revenue-sharing agreement by reducing the number of traffic citations issued, any expected revenue stream was always necessarily contingent on the citizens of the state violating the law in certain numbers. That contingency tends to suggest that the parties have no 'vested right' in a particular level of revenue."

Cooper found that changing the definition of a valid traffic citation is well within the state's legitimate powers. Cooper cited 19th Century precedent from the Tennessee Supreme Court recognizing the principle that changes in the rules of evidence do not impair contracts. Cooper noted that motor vehicle use is highly regulated, and camera vendors should expect those rules to change frequently.

"Chapter 425 does not favor one vendor over another, nor does it favor local governments at the expense of the vendors (since both parties might lose income under a revenue-sharing agreement)," Cooper wrote. "Rather, Chapter 425 would appear to favor motorists who are charged with misconduct. It enhances their ability to confront a live witness, instead of photographic evidence, at any contested hearing on the matter."