Police follow car when they notice a defective headlight and plate light. Driver slows to nearly a complete stop in busy traffic. She tells officer after stop that she was simply trying to drive safely. Officer notes glassy/red eyes, slurred speech, and lethargic reactions. There is an open container in car, but driver denies drinking and says a friend left can in her car. She does admit to smoking marijuana before and after a concert. Standard field sobriety tests are not designed to elicit evidence of drug impairment and the results are contradictory. DUI Drugs charge dismissed prior to trial.