Consumption of illicit drugs is generally underestimated as cause of road accidents. French legislation does not give the police authority to carry out their detection at once. If the regulation concerning driving and drinking is on the way of an hardening, a debate comes into being about the suppression of the penalization for consumption of some drugs whereas their involvement in road fatalities seems to be important. The influence of medicinal drugs on driver's behaviour forms the subject matter of many experimental studies, but the lack of a common methodology for testing their side effects prevents any possibility of categorization of the medicinal drugs depending of their risk for driving. This common methodology should include tests for the evaluation of risk taking and not only test for the detection of sedative effects. If self prescription and misuse of some medicinal drugs is often involved, if the prescription of some others should be allowed only for non drivers, it should be suitable to take into account the notions of therapeutical benefits and of preservation of social and professional integrity by the way of driving.