Yeah, Fort Washington was a good case a few years back. Their newly deployed systems on 210 just north of the beltway ("protecting" a school about a 1/4 mile back off the highway) were nailing a large number of big boxy vehicles. RVs and delivery trucks were getting hammered. Local auto parts guy whose fleet was particularly hit, and knew his guys were not speeding managed to win, but it was pretty ugly. Another guy showed that his RV simply could not achieve the stated speed in the time allowed. Other folks proved thier innocence using timestamps on the two pictures that come with the citation. Showed distance travelled and how many seconds it took to travel that distance. Vendor killed that degfense pretty quick by reducing the number of decimals showing to the victi, I mean offender on the citation. Still measures that, but you dont get to see it. They also had the city claim that the photos were not evidentiary in nature, even though the company operators manual for that system made a point of saying that the supplied pictures were a secondary means of proving the speed of the victim.
Do some reading, it's a pretty crazy story. Including a cameo with lying by one of our County Commissioners, who was the one fronting the lie about the purpose of the photos.
http://www.mddriversalliance.org/search/label/Forest Heights
"John O'Connor testified on Behalf of Optotraffic that photos cannot be used to show speed: "We do not use photos that are taken at two independent times to estimate speed. Why? Because it's inaccurate. You can't do it." and "The photo is actually just secondary evidence that the vehicle was there and it was in motion, that it was there at the time of the occurrence." [ O'Connor has identified himself as "Director of the Law Institute of Maryland" in his linkedin page... an organization which we could find no information for online other than a domain name registration which was opened on September 2011 and which recently expired. He lists himself as formerly the "Program Manager Automated Speed Enforcement Program Seat Pleasant Police Department", a town whose speed cameras are run by Optotraffic. That linkedin page also references the Optotraffic website (snapshot from 9/21/2012). O'Connor reportedly gave similar testimony to this effect on Optotraffic's behalf at numerous hearings.]
This testimony seems to conflict with Optotraffic's own technical document, which states that their equipment is supposed to be able to verify speed: “While the primary evidence for issuing a speeding citation is the calibrated Lane Sensor, the two photos provide the secondary evidence of speeding that is presented to the citation recipient.” and “Since a stationary object is present along with the vehicle, a photographic method also determines speed, guaranteeing fairness”.
) that will revive those flagging revenue numbers 
