At 4:20 pm, on a warm South Florida evening, a trooper stops a vehicle driven by Mary Wanna. Her vehicle had a broken tail light. When the trooper approaches, he smells the odor of marijuana emanating from inside the vehicle. Mary appears to be lethargic and has the odor of an alcoholic beverage coming from her breath. Her eyes are glossy and bloodshot and her movements are slow. The trooper asks the driver if she has been drinking. The driver responds, “No, not recently.” The trooper requests that the driver exit her vehicle. Mary slowly exits and seems to have difficulty standing without swaying. The trooper requests that she perform some “field sobriety exercises,” (also known as “roadside tests”). The trooper concludes that Mary “failed each and every test given.” He places her under arrest for DUI (Driving Under The Influence). Back at the station, Mary is asked to blow into the breath machine and blows a .000, indicating that no alcohol is present in her system. The officer then requests that Mary provide a urine sample. Several weeks later, the lab report is made available and it reveals the presence of THC, the active ingredient in marijuana. Can prosecutors prove their case?