Any officer trained and certified to use speed detection devices is qualified to use "visual estimation" against you in court as well, visual estimation within 5mph is a major part of the training and use of both radar and laser.
With a pacing charge simply ask for the speed detection calibration records. The vehicles speedometer must be calibrated and certification recorded by a 3rd party certified technician on an annual basis. Pay close attention to the vehicles identification on the records too.
It has been discovered that departments will "reuse" the calibration records of other equipment: speedometers, radar devices, etc. All speed detection devices are required an annual calibration by a 3rd party certified technician and up to date records may or may not be for the correct vehicle or device.
Yes they can, the question is can you come up with scientific evidence in court that proves they can't.
What's the first thing they ask you once it's been established you were speeding, "Do you know how fast you were going?" It's called admission of guilt and your answer will affect what happens in court...so respond wisely.
Also, no radar or laser can be used within 500 feet of a "Speed Detection Decives being used warning sign". No radar or laser can be used within 500 feet of a change in speed limit sign either.
40-14-6. Warning signs required
http://web.lexis-nexis.com/research/...a2cf5433f62d3f
Another useful law, making speed traps unlawful:
40-14-7. Visibility of vehicle from which device is operated
No stationary speed detection device shall be employed by county, municipal, college, or university law enforcement officers where the vehicle from which the device is operated is obstructed from the view of approaching motorists or is otherwise not visible for a distance of at least 500 feet.
Here's another one that can be both useful or bite you. It means you can not get a ticket for 10 or less over UNLESS the speed limit is under 35mph, you're in a school zone, or you're in a "historic district". Sounds like to me it's a good way for small old towns in rural Georgia to make a little income from a really minor speeding violation.
40-14-8. When case may be made and conviction had
(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, 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.
How many people knew about this law? You can't get a ticket on a hill over a 7% grade. Seven percent grade means the road drops down 7 feet for every 100 feet forward.
40-14-9. Evidence obtained in certain areas inadmissible; use of device on hill
Evidence obtained by county or municipal law enforcement officers in using speed detection devices within 300 feet of a reduction of a speed limit inside an incorporated municipality or within 600 feet of a reduction of a speed limit outside an incorporated municipality or consolidated city-county government shall be inadmissible in the prosecution of a violation of any municipal ordinance, county ordinance, or state law regulating speed; nor shall such evidence be admissible in the prosecution of a violation as aforesaid when such violation has occurred within 30 days following a reduction of the speed limit in the area where the violation took place, except that this 30 day limitation shall not apply to a speeding violation within a highway work zone, as defined in Code Section 40-6-188. No speed detection device shall be employed by county, municipal, or campus law enforcement officers on any portion of any highway which has a grade in excess of 7 percent.
There are countless more laws and requirements regarding radar/laser usage. Even if you are able to get the radar/laser evidence thrown out the courts may resort to visual speed estimation. This is why you hire an attorney if it's a serious violation. They know the laws and how to use them in the defendants benefit...