Speed Reading Instruments in Prince William County

Pacing, radar guns, and lidar guns are all used by law enforcement to detect speeding within Prince William County. An officer can prove the recorded speed of a target vehicle by testifying as to the results of pacing the target vehicle with the officer’s own vehicle, measuring a target vehicle with a radar device, or measuring a target vehicle with a lidar device.

Typically, when a person feels that they were not going as fast as the officer alleges, the result will just be the judge or prosecutor weighing the word of the officer against the word of the accused. However, in a minority of cases, a defense can be made which convincingly shows why the officer’s alleged speed recording was either wrong or misapplied to the target vehicle.

Read below to learn more about speed read instruments in Prince William County. And if you are facing charges, get in touch with a seasoned traffic lawyer.

Weight of Radar and Lidar Readings in Court

Radar and lidar readings are given a great amount of weight in court. This is not only because most judges are used to the radar being the primary way of measuring vehicle speeds in recent decades, but also because Virginia law itself provides that radar readings are presumed accurate if an officer has proper paperwork showing that his radar device has been calibrated within six months of it being used. Radar devices are supposedly designed to be easy to use by those with proper training, and every officer is trained for many hours using radar for traffic enforcement during the police academy. Officers are also sent back for re-training anytime their department adopts a new brand or type of radar device to be used in the field.

When radar detectors are operated properly, they are accurate as to a target vehicle’s speed within one mph in stationary mode, and within two mph in moving mode. On top of this margin of error, moving mode radars also have a one mph margin of error in relation to accurately measuring the officer’s own patrol vehicle speed. Due to all these margins of error, it is bad practice to issue speeding tickets for alleged violations of traveling just one or two mph over the limit.

Defenses to Radar and Lidar Gun Readings

In Prince William County, there are a few different legal and factual defenses to radar gun readings and other speed reading instruments in court. The most common defense to a radar gun reading is that the officer does not possess a corresponding accuracy calibration for the radar device done within six months of when it was used on the accused. Even if an officer possesses such calibration, it may not be within six months, and it may not have the proper attestations and signatures on the document to meet the legal requirements for admissibility into evidence.

Aside from whether operator error is actually common in the use of radar guns, proving operator error with radar guns in a trial is not common, especially if there is no corresponding body or dashboard camera footage to review how the officer actually used the radar device. Virginia law allows an officer’s testimony of an alleged speed reading to be accepted as sufficient evidence so long as a valid calibration certificate is produced, regardless of any unstated operator error that may have occurred.

Pacing in Prince William County Traffic Cases

Pacing is a method of determining another vehicle’s speed by matching its speed with one’s own vehicle and observing the speed necessary to match the target vehicle. Pacing involves a pursuing officer following a target vehicle both while maintaining a constant speed and a constant distance between the two vehicles. The officer then observes the speedometer of his own vehicle to inferentially determine the speed of the target vehicle.

Although pacing is the least reliable method of speed determination utilized by law enforcement, courts frequently consider and accept pacing as weighty enough to support speed-based convictions and traffic stops. Pacing is admissible evidence of speeding under Virginia law, but calibration of the police speedometer used to do the pacing will be expected by the court for purposes of legitimacy.

Defenses to Pacing

At a minimum, pacing requires an adequate length of tracking time at an exact matching speed of the target vehicle. Therefore, disputing either of these aspects of a pacing scenario could result in the pacing reading being invalidated. This can happen when an officer only testifies as to how fast they had to go to “catch up” to a passing vehicle, or whether the officer tried to pace another vehicle across different or curved lanes of traffic. Another issue is whether the pacing police vehicle had an accurate speedometer to begin with before pacing the target vehicle. Obtaining the relevant dashboard camera footage, if available, can be very helpful.

Common Misconceptions About Speed Reading Instruments in Prince William County

The most common myth about speed reading instruments in Prince William is that an officer literally has to show a pulled-over driver the displayed numbers of their speed capture that led to being pulled over in order to give out a speeding ticket. A related myth is that officers must somehow preserve the display of that captured speed reading in the device’s history or through a contemporaneous photograph of the reading. Neither of these things is required under Virginia law. Reach out to an accomplished attorney for more information.

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