Prescription drug DUI cases differ from alcohol-based DUIs primarily because there is no single numerical threshold like a blood alcohol concentration that defines impairment. Instead, these matters rely heavily on observed signs of impairment, officer testimony, and laboratory findings that show the presence of controlled substances or prescription medications. In De Lisle, law enforcement may consider behavior, coordination, and field testing results alongside toxicology reports to form the basis for charges. The absence of a standardized numerical limit makes medical context and testing methods particularly important in defense work. Because interpretation of drug levels can be complex, a strong defense often involves medical and scientific review to explain whether detected medications are consistent with impairment or reflect legitimate therapeutic use. Attention to how tests were conducted, the timing of sample collection, and chain-of-custody records also plays a major role in challenging the prosecution’s evidence. Understanding these distinctions helps De Lisle residents know what to expect and why a tailored legal response matters.