Zero tolerance laws allow the police to know what is and is not acceptable. It keeps people honest and forces them in a more gentle approach to follow the rules. It gives them a reason to listen and do what the law states rather than swaying and trying to get away with things.
Cops should all have great standards and there should be no tolerance for certain things, one of them are DUI's I feel like DUI's should be very strict, that coming from someone who lives in AZ which has one of the strictest DUI laws in the country! I don't drink though!