DUI

DUI — "driving under the influence" — is the general umbrella offense of operating a vehicle while impaired by alcohol, drugs, or a combination. In the cannabis context, DUI may be charged under (a) an effect-based standard requiring proof of actual impairment (officer observations, Drug Recognition Expert evaluation, Standardized Field Sobriety Tests), or (b) a per se standard criminalizing any driving with THC concentrations above a statutory threshold regardless of actual impairment. Most states use DUI as the operative statutory label. Penalties typically include license suspension, fines, mandatory substance-abuse assessment, ignition interlock (in some jurisdictions), and escalating exposure for subsequent offenses. Federal DUI law applies on federal property under 18 U.S.C. § 13 (Assimilative Crimes Act) and 36 C.F.R. § 4.23. Cannabis DUI prosecution is complicated because THC metabolites persist in blood and urine for days or weeks after impairment has ended, making biomarker evidence a poor proxy for active impairment. *→ See also: DWI, Per se, Implied consent