Since 1959, the Norwegian Road Traffic Act has prohibited driving unde
r the influence of drugs other than alcohol. On suspicion, the police
request a clinical examination from any driver, as well as blood analy
ses for illegal and prescribed drugs affecting driving performance. Du
ring the last few pears, then has been a marked increase in the number
of drivers suspected of be influenced by drugs (1983, n = 900; 1995,
n = 3329). The most commonly detected drugs are tetrahydrocannabinol,
amphetamine, benzodiazepines and opiates. Multi-drug use is frequently
found (> 60%). The occurrence of amphetamine (1991, ir = 216; 1995, n
= 937) and heroin (1991, n = 19; 1995, n = 172) has increased conside
rably. The frequency of drugged drivers apprehended in roadside traffi
c appears to be at least 10-fold higher in Norway than most other coun
tries. This is probably mainly due to differences between national roa
d traffic acts and the level of attention to the problem, and not to n
ational differences in the prevalence of drugged driving. (C) 1997 Els
evier Science Ireland Ltd.