Criticism of current marijuana policy typically starts by limiting the calculation of marijuana’s societal costs to the costs of arresting and imprisoning marijuana users. This way of calculating the costs minimizes those produced by use of the drug itself (i.e., the costs of treatment, drugged driving crashes, and lost productivity). When the costs related to the use of marijuana are minimized, the legalization of marijuana gives the appearance of reducing marijuana-related social costs in the same way that counting only the costs of enforcing the speeding laws and ignoring the high social costs of speeding would make legalizing speeding look like a smart idea.
Just as many people who speed do not have accidents, many people who smoke marijuana do not have problems as a result of their use, especially those who use the drug for brief periods of time and/or infrequently. The same is true for drunk driving — it is estimated that the drunk driver’s risk of an accident is about one in 2,000 episodes of drunk driving. Nevertheless, speeding and drunk driving are punishable by law because of the serious consequences of these behaviors. In all of these cases, legal prohibition serves as a reasonably effective deterrent to the behavior. For those who are undeterred by prohibition, the enforcement of the law produces escalating consequences for repeated violations.”