Alcool, drogue et délinquance

The question discussed here is clear: is the consumption of drugs (basically cannabis and drugs made from it) and/or alcohol a key causal factor in criminal behavior?
After outlining the results of major research in the field, Gilles Ivaldi confirms that the surveys show that there is an undoubted link between the use of consciousness-altering drugs and criminal activity. But, taking the study a step further, he adds an important rider: the relationship between the use of psychedelic substances and delinquency is far from straightforward. For one thing, it is hard to distinguish cause and effect; for another, they are linked by a system of underlying covariables that are sociological, psychological and demographic. Consequently the use of drugs is part of a range of peer group activities, integral to the lifestyle of young people, related to how often they go out and the level of parental supervision.
Consumption of cannabis certainly appears to be a contributory factor, much more so than alcohol, but Ivaldi acknowledges that the two are often used together, though the trends are moving in opposite directions. He reckons that all these phenomena are associated above all with the socialization of young people and membership of antisocial peer groups with a deviant lifestyle.