Q WHAT IF THE POLICE STOP ME AND WANT TO TAKE ME TO THE STATION FOR QUESTIONING? DO I HAVE TO GO WITH THEM?
A. No. If you aren't under arrest, you do not have to go to the police station. If police ask you to go with them voluntarily, you should refuse and state that you want to talk to a lawyer first. If you decide to go to the station voluntarily, you are free to leave when you want to unless the police tell you that you're under arrest.

Q. CAN A POLICE OFFICER SEARCH ME IF I'M NOT UNDER ARREST?
A. No, but if they have a reasonable suspicion to believe you could be carrying a weapon, they can pat down the outside of your clothing.

doesnt say anything about drugs.