You risk up to 10 years in prison and a fine of €150,000 if you are responsible for a fatal accident. Your vehicle may be immobilized. 6 points are deducted from your driver’s license. You also risk additional penalties: A penalty that can be added to a main prison sentence or a fine.
During a roadside check, the forces of order (police, gendarmerie) have the right to carry out screening for drug use as a preventive measure, even in the absence of an accident or offence. In the event of a fatal or bodily accident, this screening is systematic and mandatory.