Georgia Code Title 40. Motor Vehicles and Traffic § 40-14-8

(a) No county, city, or campus officer shall be allowed to make a case based on the use of any speed detection device, unless the speed of the vehicle exceeds the posted speed limit by more than ten miles per hour and no conviction shall be had thereon unless such speed is more than ten miles per hour above the posted speed limit.

(b) The limitations contained in subsection (a) of this Code section shall not apply in properly marked school zones one hour before, during, and one hour after the normal hours of school operation or programs for care and supervision of students before school, after school, or during vacation periods as provided for under Code Section 20-2-65, in properly marked historic districts, and in properly marked residential zones. For purposes of this chapter, thoroughfares with speed limits of 35 miles per hour or more shall not be considered residential districts. For purposes of this Code section, the term “historic district” means a historic district as defined in paragraph (5) of Code Section 44-10-22 and which is listed on the Georgia Register of Historic Places or as defined by ordinance adopted pursuant to a local constitutional amendment.