Adam MacLeod is an associate law prof at Faulkner Christian University in Montgomery, Alabama: when he received a speeding ticket generated by a traffic camera for a time when he knew he hadn't been driving his car (he'd been lecturing at the moment when the picture was snapped), he decided he would fight it to the bitter end.
The magistrate judge who heard MacLeod's initial case ruled against him, but the Circuit Court judge was alarmed to hear a cop admit that he had "signed an affidavit under the pains and penalties of perjury alleging probable cause to believe that Adam MacLeod committed a violation of traffic laws without any evidence that was so."
MacLeod won, but the city stonewalled when he asked for his money back (they'd made him post a cash bond equal to double the traffic fine in order to fight the ticket).
Traffic camera laws are popular in part because they appeal to a law-and-order impulse. If we are going to stop those nefarious evildoers who jeopardize the health of the republic by sliding through yellow lights when no one else is around and driving through empty streets at thirty miles per hour in twenty-five zones, then we need a way around such pesky impediments as a lack of eyewitnesses.
Yet traffic cameras do not always produce probable cause that a particular person has committed a crime. To get around this "problem" (as a certain law-and-order president-elect might call it), several states have created an entirely novel phylum of law: the civil violation of a criminal prohibition. Using this nifty device, a city can charge you of a crime without any witnesses, without any probable cause determination, and without any civil due process.
In short, municipal officials and their private contractors have at their disposal the powers of both criminal and civil law and are excused from the due process duties of both criminal and civil law. It's a neat trick that would have made King George III blush.
That Time I Turned a Routine Traffic Ticket into the Constitutional Trial of the Century
[Adam J. MacLeod/The Public Discourse]
(via Naked Capitalism)