A new study now says that cannabis users are more likely to commit violent crimes.
The project is the first of its kind to demonstrate that cannabis is not only linked with violent crime but is the root cause of it as well.
According to researchers cannabis usage causes violence. They found no evidence that the link is the other way round.
The academics said the effect of cannabis use was clear and not diminished by other factors such as patients who were heavy drinkers of alcohol.
The study comes post a series of American states having decriminalised cannabis, despite it being stronger and more potent that the hash smoked by hippies in the sixties. The move was backed by a number of influential figures including Richard Branson, Sting and former Deputy Prime Minister Nick Clegg.
The study, by five researchers from institutes from Montreal, Canada, found out that patients who were using cannabis were