In November 1996, voters in Arizona and California approved the legal use of marijuana formedical purposes. Other states are likely to follow the same pattern. This change in the use of marijuanareflects the changing public (societal) attitudes towards the use of this drug. In Canada, society mustexpress its views through different mechanisms, e.g. lobby groups. The changes which occurred inArizona and California are troublesome, at least from a pharmacological point of view. The medical useof drugs should be based on the scientific evidence which balances benefit and risk, i.e. evidence-basedmedicine. Society can decide on the societal risks that are acceptable, but not on the scientific validity ofdata.