I watched a guy try to use the argument once, simply to prove that there WAS some error. WA's "speed trap" law has a provision that states that devices are "limited to devices or observations with a maximum error of not to exceed five percent using the lapsed time during which such vehicle travels between such limits." He argued that the cosine effect produced an error greater than 5% in his situation. The judge pointed out that RADAR does NOT use the "lapsed time" method of calculating speed -- GUILTY!
Barry
A person could use it to attack its accuracy though .. and just not bring up the fact that it favors the driver ...