State Per Se DUID Laws
"Currently, there are 15 States where it is illegal per se to operate a motor vehicle with certain drugs in one’s system.
"Three of those States (Nevada, Ohio, and Virginia) have determined that driving with specific cutoff levels of certain prohibited drugs or substances other than alcohol is a per se violation of its DUI statute.
"Of the 15 States, 12 States (Arizona, Delaware, Georgia, Illinois, Indiana, Iowa, Michigan, Minnesota, Pennsylvania, Rhode Island, Utah, and Wisconsin) do not tolerate any presence of a prohibited drug or substance in a driver’s body while the person is driving. The specific drugs prohibited in these States vary (see Appendix B). In these States, any amount of prohibited drug found in the blood or urine of a driver while operating a motor vehicle is a per se violation of those States’ DUI statutes. These States were the major focus of this study.
"Additionally, in 5 States (California, Colorado, Idaho, Kansas, and West Virginia), it is illegal for any drug addict or habitual user of drugs to drive a vehicle in that State.
"Two States (North Carolina and South Dakota) make it illegal for any people younger than 21 to drive with any amount of a prohibited drug or substance in their bodies."
Addendum: In 2012, voters in Washington state approved Initiative 502, which legalized adult personal use of cannabis. According to the initiative's sponsors, "Initiative 502 establishes a new DUI “per se” limit of 5 nanograms of active delta-9-tetrahydrocannabinol (THC) per milliliter of whole blood (5 ng/mL)."
Lacey, John, Brainard, Katharine, and Snitow, Samantha. (2010). Drug Per Se Laws: A Review of Their Use in States. (DOT HS 811 317). Washington, DC: National Highway Traffic Safety Administration, p. 1.
"I-502 Backgrounder - Driving Under the Influence of THC," New Approach Washington, July 26, 2012.