Imagine having a night out with friends. You drew the short straw to be designated driver, so everyone piled into your car and you set off for an evening of dinner, drinks and dancing. Halfway through the night, as you were shuttling everyone to the next bar, a police officer pulled you over. You knew you were safe from a driving while intoxicated charge since you had not had a drop of alcohol, so it came as an unexpected shock when the officer put you in handcuffs and tossed you in the backseat of a squad car. The police had found a bag of marijuana in your car.