A police officer can only conduct a pat down of clothing if it’s suspected that someone is armed and dangerous. Also, in most cases, he can only pat down for weapons, not drugs. However, if someone gives the officer a reason to suspect that someone has drugs on him/her, this constitutes probable cause that could give rise to a lawful pat down and search. The key here is to stay calm, always be polite, and never give the officer a reason to suspect criminal behavior.