Contest a speeding ticket by finding out what type of state law governs speed limits and what measurement method was used by the officer who issued the ticket, says Nolo. Present a defense that proves a ticket was incorrectly issued under state law or a vehicle's speed was incorrectly measured.
The five methods of measuring a vehicle's speed are pacing, laser, radar, aircraft detection and VASCAR, or Visual Average Speed Computer and Recorder, according to Nolo. Dispute the results of radar and laser detection by demonstrating human error or equipment malfunction. A ticket issued by an officer who used pacing is contested by showing the officer did not travel a minimum distance. If VASCAR is used, argue a ticket by proving an officer was unable to see clearly or there was an error in his reaction time. Contest tickets resulting from aircraft monitoring by demonstrating an error in the pilot's reaction time or a loss of view.
The three types of speed limits used in various states are called basic, presumed and absolute, explains Nolo. Drivers in states that have basic speed limit laws can challenge a ticket by proving they were not driving too fast for conditions. Presumed speed limits allow drivers to exceed the posted limit if they can conclusively show that the speeding was not dangerous. Absolute limits are used in most states and do not allow any leeway or interpretation of dangerous versus safe driving.