Rule number one is your answer to the question, "Why were you speeding?" Simply reply:
"I was not speeding Officer, I was sitting exactly on the posted speed limit"
Rule number two is your answer to the Officer if he persists in repeating question 1 by saying his equipment (Radar / Laser) has shown that you were speeding. Simply reply,
"I was not speeding Officer, if your equipment says I was then I would strongly suggest that it is faulty. Will you show me the last infringement notice you issued so I may compare to see if their speed was the same as the one you are claiming I was doing?"
In most cases, the policeman will show you your reading but refuse to show you his or her previous infringement fine, citing that he is not obliged to do so.
The third rule is perhaps the most important of all. Under the National Safety Committee guidelines for the use and implementation of Police Speed detection devices, the police are only supposed to be operating them in known "Black Spot" or high accident areas. Innocently ask the question to the policeman,,
"Why are you operating this speed detection device in this area? Is it a known black spot or high accident risk area?"
If you follow the above rules you will stand a good chance of winning your case in court should you wish to defend the infringement. The justice system is there for all of us, not just the police. If you win it costs you nothing!