Radar Speed Detection
The speed in reckless driving cases is often determined by Radar. A radar gun is a Doppler radar that can be either hand held and pointed at a vehicle or mounted in an officer’s cruiser. An officer can employ both stationary and moving Radar. The gun measures the speed of a vehicle by utilizing the Doppler effect.
How it Works
The Doppler effect, or Doppler shift, is the change in the frequency of a wave from the viewpoint of an observer relative to the source of the wave. So, for instance, if a car is driving toward you with its horn blaring, the frequency of sound waves will be higher as the car approaches you, and lower as the car recedes. Most people have experienced the Doppler effect with sound without realizing it. This video is a great example of how the effect works with sound.
In order to measure the speed of a car, the Radar gun sends out a radio signal in a narrow beam and then receives the reflection of the signal as it bounces off the vehicle. If the car is moving toward or away from the Radar gun, the frequency of the reflected waves will be different than the signal sent out from the Radar gun. With that information, the gun will calculate the speed of the vehicle.
Defenses to Radar Speed Detection
There are a number of defenses to the results obtained from a Radar gun. First, there are a number of technical requirements that the government must meet in order to admit the results into evidence. The radar gun must have been calibrated with the 6 month period prior to the date the ticket was issued, and the officer must have checked the accuracy of the gun. Even if the officer does have a certificate of calibration for the Radar gun, it is unsettled as to what witnesses the government must present in order to introduce a certificate of calibration for the radar gun. There is case law to support the argument that the actual technician who calibrated the Radar gun must be present in court.
Beyond the issue of calibration, there are a number of ways to call into question the accuracy of the result of the Radar gun in each particular circumstance. Environmental and operational conditions can interfere with the functioning of the device, giving an inaccurate reading. For instance, the fan of the cruiser’s air conditioner, another moving vehicle that is reflecting the radar beam, or shadowing for moving radar can all cause inaccurate readings.
This equipment is common among both local police and state troopers in Virginia and frequently used to determine speed of vehicles for speeding and reckless driving charges. Officers will typically make a notation on the speeding or reckless driving ticket to indicate what method was used for speed detection. For Radar, an officer will often write “Rad” or “RD” on the ticket.
Reckless driving in Virginia is a class one misdemeanor. All crimes must be proved beyond a reasonable doubt. Contact the attorneys at Henson Pachuta, PLLC for a free consultation by phone at 703-822-4701 or at 4011 Chain Bridge Road, Suite 200, Fairfax, Virginia.
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