Driving in Illinois with any measurable amount of marijuana in your blood or urine is a misdemeanor under Section 11-501(a)(6) of the Vehicle Code if the use or consumption of cannabis was “unlawful.” But under Section 11-501(d), the offense becomes the Class 4 felony of aggravated DUI, punishable with a sentence of one to three years in prison, if prosecutors can prove two facts: (1) the person violating Subsection (a) was “involved in a motor vehicle accident that resulted in great bodily harm or …