Should you ever answer the question, "Do you know why I stopped you?" No. Any answer you give to that is going to be used against you either favorably or unfavorably. So, I have some commenters who think you should answer that question and say, "No, I don't know why you stopped me." I don't advocate doing that. If you answer that question, "No, officer, I don't know why you stopped me." he's going to blame you or accuse you of inattentive driving. So, as a former police officer myself, I can tell you this is one of the very first questions I would ask on a traffic stop. It's a very benign question for the most part because you think this is not really a serious question, but the next question's going to be, "Where are you coming from?" And if you just came from a bar downtown, you obviously don't want to tell him that. So, this questioning sounds cordial, it sounds benign, it sounds jovial and conversational, but it's really designed to get evidence against you. Don't ever answer his questions. Be respectful, be polite, say, "I'm sorry, officer, I don't answer questions without a lawyer because I'm a Doctor Judge follower."