"Cannabis remains the main substance involved in arrests for drug-related offences, regardless of the grounds for arrest, accounting for 90% of arrests for use and 70% of use-dealing and
trafficking cases in 2011.
"Way behind cannabis, heroin and cocaine are the main substances involved in drug-related arrests (accounting for 5.4% and 3.5% of usage-related arrests, respectively).
"We should point out the relative importance in France of the number of arrests related to the misuse of medicines (particularly HBD, aka Subutex®, but also unspecified substances, used in spite of the absence of any proof of a prescription), and those for hallucinogenic mushrooms."

Source

l'Observatoire francais des drogues et des toxicomanies (OFDT), "2012 National Report (2011 data) to the EMCDDA by the Reitox National Focal Point: France: New Development, Trends and in-depth information on selected issues (Saint-Denis, France: OFDT, 2012), p. 138.
http://www.ofdt.fr/BDD/public…