Georgia has a number of restrictions on local law enforcement regarding the use of speed detection devices. It is worth noting that these laws were motivated by the bad press the state got in the late 1960's from the traffic operations of law enforcement in the south Georgia community of Ludowici. That tale is told much better than I could in an article published in The Oxford American. At that time, the community was on the primary north-south artery for Northerners traveling to and from the sunny beaches of Florida. With a remote controlled traffic light and other underhanded law enforcement techniques, the town tried to make sure they got a part of those vacation dollars.
Each law enforcement agency in the state has to obtain a permit from the state to operate speed detection equipment, whether radar or laser. Those permits are only available to qualifying full time law enforcement agencies. They require the local government authority to post warning signs that such equipment is in use. Operators of the equipment must be properly trained and permitted. Equipment must be calibrated according to a strict schedule. These rules do not apply to the Georgia State Patrol. the state permit details the roadways on which the agency is authorized to operate speed detection devices.
A stationary patrol vehicle can only operate a speed detection device if the patrol vehicle is visible for a distance of at least 500 feet. In other words, no hiding behind shrubs, billboards or other obstructions. OCGA 40-14-7.
County, city and campus officers cannot make a charge unless the speed detected is more than 10 mph over the speed limit and a person cannot be convicted of speeding 10 mph or less over the speed limit based on a speed detection device reading. OCGA 40-14-8. The only exception to this rule is in school zones, marked historic districts and properly marked residential districts. A district is not considered a residential district if the speed limit is 35 miles per hour or more. The school zone rule covers from one hour before school start, during the school day, and up to one hour after school ends. That exception can be extended for afterschool programs.
Speed detection devices cannot be used by local law enforcement within certain distances of the required signage. The distances are 300 feet from a reduction of speed limit sign inside city limits or within 600 feet of a reduction of speed limit sign outside city limits. OCGA 40-14-9.
Speed detection devices cannot be used by local law enforcement on any portion of a highway which has a grade in excess of 7 percent. Note: the state permits will often exclude these sections of roads from the state permits, so that is one way to determine if the grade is steep enough to qualify. For initial determinations, I use a four foot level and a yardstick. If it is a state highway, you can often send off to Georgia DOT for the road plans that will show the grade of the road. Otherwise, if I think the road is too steep, I will then hire a surveyor to shoot the elevations in segments of the roadway, so that I have a witness and an exhibit to show the grade. I did this several years ago for a local hill and beat the speeding ticket and then was able to use the survey to beat a DUI charge where the reason for the stop was speeding based on radar. The grade rule applies to both stationary and moving speed detection devices.