I was arrested in Arizona in 2001 for smoking pot. I was not selling it or distributing it. I was on a road trip with some friends and the night clerk at the hotel I was staying in called the cops because he smelled the joint we had smoked. The cops came and arrested all of us. Here's the really fun part! At the time Maricopa county was trying to be all "law and order" and cracking down on drug crime. They had made any possession, no matter how small, a felony. So I was booked and charged with TWO FELONIES because we smoked a joint an my buddy had a pipe in his bag. Paraphanilia, no matter how small, was also a felony. Now because I had no prior convictions, I was offered a pre-trial diversion program. In exchange for taking drug counseling courses and passing drug tests (that I had to pay out of my own pocket) and paying a rather large fine, I was able to avoid trial and have my record expunged. Thankfully, I was not some broke kid who didn't have the $2000+ to pay the fine and take the courses. Otherwise I would have had to go to trial for two felony counts.
Maybe in some places, cops don't arrest you for marijuana but I can assure you that is not the case everywhere. Drug offenders are big profit for police departments and the prison system. They're often much easier and safer to arrest than violent criminals.
