For the purposes of the study, drivers of motorised vehicles are randomly stopped and interviewed and breath alcohol is recorded. Also, an oral fluid sample is taken and psychoactive substances are investigated in the laboratory. For cases, drivers injured in traffic accidents are asked to participate to the study. A whole blood sample and, if possible, an oral fluid sample is taken and psychoactive substances are determined in the laboratory. Also, people diseased in road traffic accident are included in the study. The information required for these subjects are taken from a register database.