"For 20 intoxicating substances, it has been documented that use entails an increased risk of a road accident. Concentration limits corresponding to a blood alcohol level of 0.2 mg/ml have been adopted for these substances.
"Sentencing limits corresponding to 0.5 mg/ml and 1.2 mg/ml
"For 13 of the 20 substances, sentencing limits have been adopted that correspond to the intoxication normally associated with a blood alcohol level of 0.5 and 1.2 mg/ml, respectively. There is documentation that intoxication becomes more pronounced at higher concentrations of these substances. As for alcohol, the development of tolerance to such substances is not taken into consideration.
"The limits are linked to one individual drug, and not to combinations of drugs. If several substances are found in a case, and the concentration of one of the drugs is higher than the highest sentencing limit, it will not be necessary to carry out an individual (expert) assessment."
Norwegian Institute for Alcohol and Drug Research, "The Drug Situation in Norway 2012: annual report to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA)," (Oslo, Norway: December 2012), p. 81.