The infraction or offense of speeding is committed when the driver of a motor vehicle exceeds the posted speed limit or exceeds the speed limit that is reasonable and prudent under the circumstances or conditions—such as the road (straight, curved, wet, dry, icy, flat, hilly); the weather (clear, foggy, raining, snowing); and the visibility (smoke from a grass fire or a tractor trailer obstructing the view).

Speeding laws (and enforcement) vary from state to state and among cities and towns (local ordinances) and are usually located in a state’s statutes. The penalty for speeding is usually a fine and demerit points added to the driver’s license or driving record.

To measure the speed of a moving vehicle and issue speeding tickets, police officers generally use radar guns that rely on radio signals and the Doppler Effect, or Light Detection and Ranging (LIDAR) technology that relies on lasers rather than radio waves. These devices require training on their proper use and regular calibration to be accurate.

In Pennsylvania (PA), the offense of speeding occurs when a driver operates a vehicle at a speed exceeding the posted limit or drives at a speed that is not reasonable and prudent given the current conditions, such as road characteristics, weather, and visibility. Pennsylvania's Vehicle Code outlines the specific regulations and penalties for speeding. Penalties for speeding typically include fines, which can vary depending on how much the driver exceeded the speed limit, and points added to the driver's license. Accumulating too many points can lead to license suspension. Law enforcement officers in PA use radar guns and LIDAR technology to measure vehicle speeds. These devices are subject to requirements for proper training in their use and regular calibration to ensure accuracy. It's important to note that in Pennsylvania, only state police can use radar to enforce speed limits, while local police rely on other methods such as VASCAR or ENRADD.