It was not "zero tolerance" in NYC. It was based on as stated by others, broken windows theory. We did not run out and arrrest anyone and everyone. We systematically cleaned up the streets. We collared those who were or had potential to be criminals. Not everyone.....and yes....you CAN tell the difference for the most part.
The theory is your arrest the low level criminals and don't stop. Thus, they don't have an opportunityto go on to bigger things. Crime is progressive. Studies have shown very few have gone from John Q. Citizen to bank robber or mass murder (unless they have psychological problems). A guy doesn decide today he will do a robbery. He builds up to....jumping the turnstyle....pick-pocket. steal from CVS, purse snatching and then a robbery. The theory goes through all crimes. Thus you hit them when they start...jumping the style...and prosecute. But it takes more than the cops. The ADA's need to follow through, not plea bargin, and the judegs need to give the full sentance...not teh minium. It is a team effort!
-In God we trust. All others, put your hands on the car and don't move.