Establishing legal limits for driving under the influence of marijuana

Table 2 Types of drugged driving legislation and legal Δ⁹-tetrahydrocannabinol (THC) thresholds for drivers in European countries

Country	Legislation	Legal THC limit
Belgium	Two-tier	1.0 μg/L in blood serum
Denmark	Two-tier	1.0 μg/L in blood
Finland	Two-tier	THC: 1.0 μg/L in blood THC-COOH: 5.0 μg/L in blood
France	Two-tier	1.0 μg/L in blood
Germany	Two-tier	1.0 μg/L in blood serum
Greece	Impairment	1.0 μg/L in blood
Ireland	Impairment	THC: 2.0 μg/L in blood THC-COOH: 5.0 μg/L in blood
Italy	Per se	THC or THC-COOH: 0.5 μg/L in blood
Luxembourg	Impairment	2.0 μg/L in blood serum
Netherlands	*	3.0 μg/L in blood** 5.0 μg/L in blood serum
Norway	Impairment	1.3 μg/L in blood***
Poland	Per se	THC: 2.0 μg/L in blood THC-COOH: 50.0 μg/L in blood
Portugal	Per se	THC: 3.0 μg/L in blood THC-COOH: 5.0 μg/L in blood
Slovenia	Per se	THC: 0.3 μg/L in blood serum THC-COOH: 5.0 μg/L in blood serum
Switzerland	Per se	1.5 μg/L in blood
United Kingdom****	Impairment	THC: 2.0 μg/L in blood THC-COOH: 10.0 μg/L in blood

*Impairment as of 2011, but a proposal for a two-tier system has been implemented.
**Recommended by Netherlands Advisory Committee.
***Norway specified THC levels comparable to BAC (with regard to severity of impairment): 3.0 μg/L in blood is comparable to 0.05% BAC; 9.0 μg/L in blood is comparable to 0.12% BAC.
****Initial drug screening is conducted via Drugalyser oral swab tests. A positive test could lead to a blood sample test to quantify THC level.
Abbreviations: THC Δ⁹-tetrahydrocannabinol, THC-COOH carboxy-Δ⁹-tetrahydrocannabinol.
Sources: Verstraete A, Knoche A, Jantos R, Skopp G, Gjerde H, Vindenes V et al. Driving under the Influence of Drugs, Alcohol and Medicines (DRUID): Per se limits - Methods of defining cut-off values for zero tolerance. 2011. Accessed July 20 2014; Wolff K, Johnston A. Cannabis use: a perspective in relation to the proposed UK drug-driving legislation. Drug Test Anal. 2014; 6(1–2):143–54.

ISSN: 2197-1714