Influence of psychotropic drugs on traffic safety is a great problem at present. Forensic expertise of their influence on the ability to drive a car is much more complicated than in alcohol. Elimination of these compounds does not make us possible calculation of the drug blood level at time of accident, their influence on psychic functions is much more variable than in alcohol and we can see here toxic psychoses more often than at alcohol, too. Authors conclude that zero blood level of “illicit drugs” is essential condition of ability to drive a car.

Key words: non-alcoholic psychotropic substance – illicit drug – traffic safety – car driving – psychiatric forensic expertise