When Marijuana is Legal

BRISBANE – What will happen if Californians votes this November to legalize marijuana use by any adult over the age of 21 years? Let’s ignore for the moment the vexed constitutional issues that will be raised if a US state enacts legislation that conflicts with federal law. Let’s focus instead on what may happen if the law changes as the referendum proposes.

If we are to believe the referendum’s supporters, all Californians will be winners. The change will legitimize marijuana’s de facto legal status since passage of Proposition 215 in 1996. It will thus reduce state expenditure on enforcing a widely violated law; remove marijuana growing and selling from the black market; enable any adult who wishes to use marijuana to do so; and introduce a tax on legal marijuana sales that will fill state coffers with revenue that formerly went to illegal growers (so long as there is no large-scale tax evasion).

By contrast, opponents predict that the change will increase rates of marijuana use, and thus magnify the harm arising from that use. The adverse consequences of greatest concern include more marijuana-related road traffic accidents and deaths; more psychoses and other serious mental health problems among heavy users; and heavier marijuana use by young people, negatively affecting their life chances. These effects, they argue, will more than offset any gains from tax revenue and savings from law enforcement.

It is difficult to know who is right, because no other country has adopted this policy. The Netherlands, which is popularly believed to have legalized cannabis use along these lines, has in fact tolerated only small-scale retail sales of marijuana in a limited number of coffee shops in its larger cities. Marijuana cultivation remains illegal and coffee shop sales are regulated – more strictly in recent years in response to complaints from neighboring countries about “drug tourism.”

Nevertheless, some broad predictions can be made. First, openly tolerating a market in a previously illegal commodity will expand the number of users, especially if the retail price is lower than the black-market price (as is proposed in the Ammiano Bill currently before the California legislature). Use may not increase immediately, but it will over time, because marijuana will become more freely available, much cheaper (in order to discourage the persistence of a black market), and its use will be implicitly condoned.

Experience with alcohol suggests that marijuana will be available to underage users (as it is now), whatever the minimum legal age. Thus, legally available cheaper marijuana will probably mean more use by more young people, and probably more daily use later into adulthood. In general, the more people who use a drug, the larger the number of problem users there will be (on the reasonable assumption that problem users comprise a fixed proportion of all users).

If current estimates are correct, around 10% of users (and one in six who start in adolescence) may become dependent on marijuana – that is, find it difficult to control or discontinue their use. A minority of these problem users will seek professional help to quit.

Dependent marijuana users are more likely to experience road and workplace accidents (if they drive or work while intoxicated); increased respiratory disease (if they smoke marijuana); exacerbations of some serious mental disorders; and impaired school and work performance.

It is uncertain how far these adverse effects can be mitigated by preventive measures such as implementing roadside drug-testing programs, persuading users to use vaporizers rather than smoke joints, discouraging young people from using marijuana, and encouraging early treatment for problem users. Experience with alcohol suggests that these approaches may modestly reduce, but not eliminate, the harms associated with use, especially if sellers are allowed to promote their wares.

Indeed, the scale of any increase in marijuana use will critically depend on how tightly regulated marijuana sales are – how many licensed growers there are, the number of sales outlets, their locations and trading hours, eligibility requirements for use, content of THC (marijuana’s psychoactive ingredient), and how much promotion and advertising is allowed. If marijuana were allowed to be marketed much like alcohol is now, we could expect more problem users than if it were regulated more like pharmaceutical drugs (say, by requiring users to be licensed; restricting the number of sales locations, hours of sale, and licensed growers; and imposing high rates of taxation on higher-THC marijuana).

It will be a major policy challenge to get this balance right. Greater restrictions would provide incentives for illegal operators to remain, while less restrictive regulation would discourage black marketeers, but at the price of increasing the number of users and problem users.

Marijuana policy involves a choice between the evils of current repressive policies and the evils of increased use under a legal market. Californians will have to decide how much weight to give to respect for adult liberty, protection of minors, avoidance of a large-scale black market, fiscal considerations, and protection of marijuana users’ health. If they vote for legalization, it will probably be 20 years or more before anyone can say whether, on balance, they decided wisely.

Wayne Hall is a National Health and Medical Research Council Australia Fellow at the University of Queensland Centre for Clinical Research, Brisbane, Australia.

Copyright: Project Syndicate, 2010.
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