Motorists in Maryland have been receiving tens of thousands of illegal and inaccurate photo radar citations. According to an audit report performed on behalf of the city of Baltimore, upwards on ten percent of speed camera tickets issued were bogus. That represents a doubling of an earlier admission by the speed camera operator Xerox that the error rate was 5.2 percent. Other jurisdictions have run into similar problems.

Baltimore eventually dumped Xerox over the problems, but it hired URS Corporation to perform an independent review. The resulting report, completed last April, was withheld from the public and was obtained by the Baltimore Sun newspaper.

URS was given access to the Xerox database of citations issued, and the auditors came up with a "plausibility check" to measure the claimed camera speed reading against the distance traveled between the first and second photograph. In a half second, a car going 20 MPH travels 14 and half feet -- about a car length. At 40 MPH, the vehicle travels two car lengths, which is a readily discernible difference.

The study double-checked 933 tickets in total, examining the first 26 citations issued at each camera location after May 15, 2012 -- a date not included in the Xerox audit.

Twenty-five of the 37 cameras issued bogus tickets, with 10.6 percent of the citations overall found to be faulty. Another 25.6 percent were found to be questionable. The worst offenders were the 5400 block of Loch Raven Boulevard (58 percent erroneous), the 6500 block of Eastern Avenue (45 percent), 1098 Caton Avenue (35 percent), 6000 block of Hillen Road (31 percent), 4862 Erdman Avenue (27 percent).

The audit notes several factors that might explain the accuracy problems. The ticket photos often show multiple vehicles. In many cases, the wrong vehicle was cited. Often the camera was found to be incorrectly positioned.

Legal issues have haunted other jurisdictions. On Wednesday, Prince George's County admitted that it had unlawfully allowed its private contractor to issue 2059 tickets worth $82,360 near St. Ignatius Loyola School on Brinkley Road in Fort Washington. The local television station WUSA noticed that the county failed to meet the legal requirement to advertise the camera location prior to activating the device. As a result, the county agreed to a full refund of all improperly issued citations.