I know radar makes mistakes. Can I use it as a defence?
The short answer is yes. But there is a lot more to it than just saying to the judge “since radar makes mistakes therefore I am not guilty”. You are not a radar expert approved by the court to say this. Even if the judge knows pretty well that radar does make mistakes, your opinion is of no value since you are not an expert in this field. You must get the real radar expert, the cop, to admit by himself that radar makes mistakes. This can only be achieved by carefully and intelligently planned cross-examination. Anything you can get from the police agency by a public records request will be useful to establish a baseline that the radar unit and its operator must meet.