Establishing legal limits for driving under the influence of marijuana

Table 1 Legal Δ⁹-tetrahydrocannabinol (THC) thresholds for drivers in states with per se laws

State	Legal THC limit	Collected specimen	Year effective
Colorado	5.0 μg/L in blood	Blood, urine, or OF	2013
Iowa	THC-COOH: 50.0 μg/L in urine	Blood or urine	2010
Montana	5.0 μg/L in blood	Blood	2013
Nevada	THC: 10.0 μg/L in urine, 2.0 μg/L in blood THC-COOH: 15.0 μg/L in urine, 5.0 μg/L in blood	Blood, urine, or other bodily substance	2003
Ohio	THC: 10.0 μg/L in urine, 2.0 μg/L in blood THC-COOH: 35.0 μg/L in urine, 50.0 μg/L in blood THC-COOH in combination with alcohol or other drugs: 15.0 μg/L in urine, 5.0 μg/L in blood	Blood, urine, or other bodily substance	2006
Pennsylvania	THC or THC-COOH: 1.0 μg/L in blood or urine	Blood or urine	2011
Washington	5.0 μg/L in blood	Blood	2013

Abbreviations: OF oral fluid, THC Δ⁹-tetrahydrocannabinol, THC-COOH carboxy-Δ⁹-tetrahydrocannabinol.
Sources: (NORML). Drugged Driving. Washington, D.C. 2014a. http://norml.org/legal/drugged-driving. Accessed July 15 2014.; Lacey J, Brainard K, Snitow S. Drug Per Se Laws: A Review of Their Use in States. Washington, D.C.: National Highway Traffic Safety Administration (NHTSA). 2010. Accessed July 15 2014.; Avila EN. Minimum Levels of Controlled Substances or Their Metabolites in Blood to Establish Presence of Controlled Substance. Pennsylvania Bulletin. [2011] April 30. Accessed July 23 2014.; [Wash Rev Code § 46.61.502]); Walsh JM. A State-by-State Analysis of Laws Dealing With Driving Under the Influence of Drugs. Washington, D.C.: National Highway Traffic Safety Administration (NHTSA). 2009. Accessed July 12 2014.

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