Why do officers need to have a visual estimation of speed prior to using a speed detection device?

Having a visual estimation of speed prior to using a speed detection device is essential for establishing probable cause. When officers observe a vehicle that they suspect is speeding, their initial visual assessment allows them to form a reasonable belief that a violation may be occurring. This visual cue is crucial because it helps officers support their decision to use an electronic speed detection device, ensuring that they are acting on more than just random equipment readings.

Establishing probable cause is imperative for legal proceedings that may follow. If an officer can articulate their initial observations alongside the data collected from the speed detection device, it creates a stronger case for enforcement actions. This combination of visual assessment and technological verification ensures that traffic laws are enforced fairly and accurately.

While visual estimation might contribute to considerations of the chase dynamics, roadway conditions, or vehicle maintenance, those factors do not fulfill the immediate legal requirement necessary for initiating a traffic stop based on speed. The primary focus rests on building a justified reason to act, which is rooted in the officer's visual estimation of the vehicle's speed.