3 Ways Great Virginia Reckless Driving Attorneys Challenge Traffic Radars

Northern Virginia Reckless Driving Attorney:
3 Ways Traffic Radars are Vulnerable to Attack in Court

Northern Virginia reckless driving attorneyRadar technology, like all technology, has flaws. In the United States, radar technology has long been used by police departments to issue speeding tickets. In Virginia, speeding just 20 above the posted limit, or above 80 mph, is a crime. Strict laws like the reckless driving laws here in the Commonwealth of Virginia as they pertain to the criminalization of speeding, is one reason why Fairfax County is home to some of the most revered reckless driving attorneys in Virginia.

These defense attorneys not only understand how the devices work: how they fail; how they are used correctly – and incorrectly; and what may ultimately lead to the finding that the evidence does not support guilt beyond a reasonable doubt.

Our Fairfax reckless driving attorney recently published a page devoted to reckless driving cases in Fairfax County. This post touches on 3 ways radar units are attacked in court…but see the Fairfax-specific page if you want to learn more about radar, laser radar, moving-mode radar, and the pace method.

If you skip the Fairfax County page, here is a synopsis of the relevant portion:

Fairfax criminal lawyer and reckless driving attorney, Brenton Vincenzes, mentions various ways police officers determine speed: stationary radar; moving-mode radar; laser devices (LIDAR); the PACE method; and visual estimation…and ways they fail due to inherent flaws and/or operator error.

How do Virginia reckless driving attorneys attack the accuracy of a radar unit?

Below, you will learn about 3 ways a Northern Virginia criminal lawyer might go about attacking a radar device and the operator at a trial. These 3 are by no means exhaustive, and you can read much more about attacking these devices by reading our advanced reckless driving defense post, our Virginia reckless driving information page, or our Fairfax reckless driving information page.

3 Ways a Northern Virginia Reckless Driving Attorney Might Challenge a Radar Reading

Margin of Error

Aside from operator error, calibration requirements, and something called the Cosine Effect, margin of error is an important technical flaw that can be very helpful in a close case:

  • Some stationary radar units have a margin of error of about 1 mph.
  • Moving-mode radars, however, often have a slightly higher margin of error – about 2 mph, in many cases.

This may seem like a moot point if the alleged speed is much higher than the “reckless driving by speed” threshold of 20 mph over the limit, but in a case where it is alleged that the motorist was driving 76 mph in a 55 mph zone, it could be worth pointing out to the prosecutor in negotiations, or to the judge when making a closing argument.

Fluctuation in Speed

Radar units measure frequencies based on reflections of a waves they emit off of a target vehicle.

This emission is sometimes referred to as the radar integration cycle. This time frame is usually .1 , to as long as 2 seconds for older devices.

If the target vehicle alters its speed (accelerates, brakes) faster than (about) 1 mph per integration cycle, then accuracy may very likely be sacrificed as a result. This fluctuation in speed is sometimes referred to as:

Speed Tolerance

Often, the model used by the officer has a speed tolerance of around 1 mph per radar integration cycle, so your Northern Virginia traffic lawyer or reckless driving attorney may quiz the officer on the stand with a line of questions meant to expose a possible inaccurate reading.


Very large vehicles targeted at close range by a patrol officer may produce a reflection so large that the radar unit incorrectly measures the harmonic of the actual echo. The result?

Possible exponentially higher speed reading than actual speed.

Thus, if your vehicle was targeted at a time when there was another large or larger vehicle near you, or if your vehicle is very large, then it may be possible that this technology flaw played a role: harmonics were processed by the device as opposed to a true echo or reflection.

In conclusion:

Fairfax County Reckless Driving charges are fairly common, compared to most other criminal violations. Since it is a crime, there are many excellent Northern Virginia criminal lawyers who can help drivers attack the reliability of a traffic radar device, or as the case may be, admissibility of certain evidence. This level of knowledge takes much studying, research, and experience. We recommend finding a local Northern Virginia reckless driving attorney who frequently handles cases in the locality of the offense. For example, if your charge arises in Fairfax County, find a Fairfax criminal lawyer or Fairfax reckless driving attorney, instead of a lawyer who practices mainly in another area, or who does not regularly handle reckless driving cases in Virginia.

Many people who face this charge for the first time are surprised to learn it is a Class 1 misdemeanor, capable of resulting in a fine in excess of two thousand dollars and up to a year in confinement. Although speed-related reckless driving cases involving drivers with great records and a relatively low speeds (20-30 over in a high mph zone, for example), the big concern for such a person often is the nature of the offense and potential conviction:

a criminal public record for life.

Fortunately, in some cases there are things one can do to enhance his or her odds to reach a favorable outcome, such as an agreement to plead guilty to a mere traffic infraction as opposed to a criminal violation. To ask our Fairfax and Northern VA reckless driving attorney about your case, do so online or call us at 703.665.3719.

See also,

Radar Speed Detection, Homing in on New Evidentiary Problems (1980) – a good read for gaining a foundational understanding of the earlier case-law and principles, most of which are still applicable today.

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Brenton D. Vincenzes is a lifelong Fairfax County resident and Fairfax Criminal Defense Lawyer. He is a member of the Virginia Association of Criminal Defense Lawyers, National College of DUI Defense, NORML, and has been awarded the following in 2014-15: Top 100 Trial Lawyer (National Trial Lawyers) Top 40 Under 40 Trial Lawyer (National Trial Lawyers) Nationally Ranked Top 10 Under 40 Defense Attorney (National Academy of Criminal Defense Attorneys) 10 Best in Client Satisfaction for Criminal Defense (American Institute of Criminal Law Attorneys) Nationally Ranked Top 1% Attorney Award Recipient (National Association of Distinguished Counsel) As a local leader, Mr. Vincenzes mentors troubled youths, volunteers his time to serve at his church, takes select pro bono clients, and strives to improve the community. Mr. Vincenzes represents men, women, and juveniles through zealous and diligent advocacy, strategic planning, and skilled trial work preparation. Mr. Vincenzes' areas of criminal law practice are broad, and include most felonies and misdemeanors such as: reckless driving, DUI & DWI, drug offenses, assault and battery, domestic violence, assault on an officer, destruction of property, alcohol offenses, firearm offenses, larceny, shoplifting, embezzlement, fraud, and other theft offenses, and moving traffic violations among others. His private legal services are available in most Northern Virginia jurisdictions, including Fairfax County, Arlington County, Prince William County, Loudoun County, Stafford County, Alexandria, Manassas, Leesburg, South Riding, and other cities and towns.


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