Pulling over a motorist can result in a simple citation or a raging gun battle. You have to be prepared for either one.
Experience is the best teacher for learning to spot contraband drugs and alcohol and drug intoxication in the field. But the cop needs a demonstrable standard for evidence. It's here that presumptive field testing for alcohol and drugs is most useful.
Encompassing everything from red curbs to alleyways, from metered parking spots to handicapped designated violators, parking enforcement is often seen as a nuisance. But it can also be a means of identifying red flags.