What are the rules governing Police stop and searches? I live in Brooklyn, NY and folks here are kinda sensitive about the Stop and Frisk police tactics due to profiling. Is Stop and Frisk a common police strategy in Switzerland?

I was down at the Sihlquai last week and observed the police 'randomly' stop and search 3 different groups. After a pat down and search of possessions, 2 of the stops resulted in all being let go. In the third, the police found a nice fat sack of ganja (5 grams at least). I was expecting the cops to slap cuffs on the guys and take him, but they just wrote him a ticket and went on their way. Seemed like a whole lot of work, just to write a ticket.