What is the legal threshold for speed detection in many jurisdictions?

In many jurisdictions, law enforcement agencies often establish a specific margin above the posted speed limit that is tolerable before taking enforcement action. This threshold allows for minor variances in speed that account for factors such as speedometer inaccuracies and the natural fluctuations in speed as drivers navigate road conditions.

The rationale behind having a speed tolerance, such as exceeding the speed limit by a certain margin, is to prevent penalizing drivers for slight unintentional infractions while still maintaining road safety. This acknowledges that not all drivers can maintain perfect adherence to speed limits at all times, especially when factors like traffic flow and speed limit signage can play roles in actual driving behavior.

Therefore, identifying a certain threshold, like 10 mph over the limit, as a standard for enforcement allows law enforcement to focus on more significant violations that are a greater concern for public safety rather than on minute infractions.