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Challenging Police Radar Gun Evidence in Traffic Court

Radar guns are valuable tools for detecting a vehicle's speed, but like all measurement devices, they are not perfect technology. In addition, they are operated by law enforcement officers and are not immune to human error.

If the police have cited you for speeding based on a radar gun reading, you can challenge the evidence in court based on the limitations of radar guns. Read on to learn more.

How Radar Guns Work

Radar guns are devices that both send and receive radio signals. They work by directing a radio signal towards a vehicle and then receiving the same signal as it bounces off the vehicle. Using the Doppler Effect, the device can calculate the speed of the vehicle based on changes in the value of the returning signal.

Many law enforcement agencies have adopted Light Detection and Ranging (LIDAR) technology. LIDAR operates similarly to radar but uses lasers instead of radio waves.

Before challenging a speeding ticket in traffic court, you need to know what speed detection device the officer used. Besides radar guns and LIDAR, some agencies may also use pacing or VASCAR to measure speed. VASCAR (Visual Average Speed Computer and Recorder) is a recent technology that determines speed by calculating the time a motorist takes to travel between two points.

Regardless of which technology the agency uses, these devices are sensitive tools of measurement that require regular calibration and adjustment. Radar guns, for example, require the use of a tuning fork to ensure the device is producing accurate readings. Device manufacturers devices recommend calibration before every use. However, some states may require testing and calibration less frequently.

Radar Gun Fast Facts

Radar guns use three types of frequency bands to transmit the radio waves used to detect speed:

  • X-bands: Not commonly used anymore and the least accurate
  • K-bands: More compact and often used in handheld radar guns
  • Ka-bands: Most commonly used by law enforcement and least susceptible to interference

Radar guns can detect a wide range of speeds, with no plausible maximum. Most radar guns can accurately measure speeds up to several hundred miles per hour. However, effectiveness depends on several factors, including:

  • The specific gun design
  • The distance between the radar gun and the target vehicle
  • Weather conditions and obstacles, such as other vehicles, trees, and buildings
  • The type of frequency band used
  • Calibration and the officer's training

Radar guns can either be digital or analog. Digital radar guns are more common now and have become the standard due to their advantages in accuracy, ease of use, and targeting range. Analog radar guns are less prevalent today, but still used by some law enforcement agencies that haven't yet transitioned to digital technology.

Officers use radar guns in a couple of different ways, depending on the situation:

  • Stationary radar is used when officers monitor traffic from a fixed location, like their police car on the shoulder of a highway.
  • Moving radar is typically mounted inside a moving police car and used while in motion.

Calibration Record Evidence

The quickest way to challenge radar gun evidence is to introduce the calibration records for the device that measured your speed into evidence in court. If the device wasn't calibrated correctly or within the required timeframe, you can create reasonable doubt that the radar reading was accurate. This in itself can be grounds for ticket dismissal.

Some officers may inaccurately believe they can calibrate a radar gun without using the tuning fork. Because of this, it is beneficial to ask whether they used the fork during calibration. If they did not, it opens up another opportunity for you to argue for a ticket dismissal on the grounds of false evidence.

Radar and LIDAR Gun Training

Most states also require officers using radar or LIDAR technology to complete approved and certified training programs before operating the devices. Another defense is to check if the issuing officer had the required training. If not, you can use the defense that the reading could have occurred due to operator error and not because you were actually speeding.

None of these arguments will automatically result in a ticket dismissal, but if you know you weren't speeding, you may want to consider challenging the citation in traffic court instead of paying the fine. Just because the police officer's radar gun showed you exceeded the speed limit doesn't necessarily mean you were speeding. Radar guns are not infallible. They can provide incorrect information if not operated or maintained correctly.

Radar Guns and Margin of Error

Radar units have a very slight margin of error. Using a margin of error argument in traffic court likely won't be useful in a complete ticket dismissal. This is because most officers won't issue a speeding ticket for going only a couple of miles per hour over the posted speed limit. The estimated margin of error for most radar guns is between one to two mph.

There are situations when bringing into question the radar gun's margin of error can be crucial. If police cite you for a major speed violation but your clocked speed is borderline for a standard speeding citation, this defense may reduce your offense classification.

Excessively high speeds can qualify for a more serious speeding ticket, often called excessive speeding or aggravated speeding. You can also face reckless driving charges in these situations.

Penalties for these types of speeding offenses are more severe than those for standard speeding tickets. Excessive speeders can expect elevated fines, driving record pointsdriver's license suspension, or even criminal charges in some cases.

Speeding Traffic Violation? Get Legal Advice

If you want to fight a speeding ticket or other traffic offense, a skilled traffic ticket attorney in your area can greatly increase your chances of having your ticket reduced or dismissed. An attorney experienced with local traffic laws can help protect your rights and build a strong defense, including challenging radar device evidence.

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