Is cannabis prohibition really the best option for reducing the harms caused by cannabis when identifying benefits is so difficult, financial costs are unknown but presumed to be substantial and collateral damage is so considerable?

Although consumption has declined recently, significant demand for cannabis has existed in Australia for more than four decades. Under current arrangements, domestic production provides some supply while most of the market is largely and inevitably supplied by criminals.

Arrests of senior drug law enforcement officials on corruption charges are an all-too-frequent reminder of the high price of trying to ignore the law of supply and demand. In contrast, the potential benefits of control of cannabis by taxation and regulation are demonstrated by the relative efficacy of this approach for alcohol and tobacco.

Despite the immense power of the tobacco industry, the proportion of Australian men and women who smoke cigarettes has declined remarkably in recent decades due to public health policies. Consequently, tobacco-related cancers and other health complications and harms are waning. Likewise, controlling alcohol by tax and regulation has seen consumption in Australia fall about 25% from its peak in the early 1980s when alcohol problems in this country were considered endemic.

The best known example of banning a commonly used drug is the alcohol prohibition era in the USA (1920-1933). Organised crime and official corruption soared but the effect on consumption was less dramatic. Prohibition in the US virtually eliminated beer, the then dominate beverage. But US alcohol consumption had been falling before 1920 and this continued in the early years of prohibition before increasing again (mainly due to spirits).

Thanks to subsequent regulation, alcohol consumption did not return to pre-prohibition levels until the 1960s. Alcohol consumption also fell dramatically in the early twentieth century in the UK and Australia which never adopted prohibition. In short, alcohol regulation worked about as well as prohibition in limiting alcohol consumption without the collateral damage of increased crime.

No significant public health figure in this country advocates prohibiting tobacco or alcohol today even though these two substances are responsible for 97% of drug-related deaths in Australia. Instead it is pretty well accepted that regulation provides many more levers than prohibition for effectively controlling use and decreasing consumption. Why then are policy makers so reluctant to consider controlling cannabis by taxation and regulation?

There are two main reasons. First, commentators maintain that controlling cannabis by regulation and taxation will lead to an increase in cannabis use and therefore associated harms. Although the evidence does not consistently or strongly support an inevitable increase in consumption when cannabis laws are liberalised, some commentators prefer to hedge their bets.

Professor Wayne Hall, for instance, has recently (‘Tackling the double standards on drugs’ Crikey. 5 June 2008) warned that cannabis consumption will increase if policy is liberalised despite publishing papers showing that this did not happen when cannabis policies were liberalised in South Australia.

And recently Miranda Devine of The Sydney Morning Herald was joined by Wayne Hall in defending strict cannabis policies even while conceding that consumption had fallen in Australia during the last decade when several states and territories introduced more liberal policies (such as infringement notices for possession of small quantities).

Second, some commentators are still reluctant to acknowledge the full extent of the damage to the integrity of our criminal justice system as well as users from our cannabis laws. In Western Australia, a much higher proportion of cannabis offenders receiving harsh penalties reported adverse effects on employment, further problems with the law and negative consequences for relationships and accommodation than South Australian offenders who only received an infringement notice.

While neither form of penalty deterred subsequent cannabis use for the vast majority, convictions had a much greater adverse social impact than infringement notices.

Wayne Hall describes my position on the benefits of regulation as inconsistent yet in 2007 Hall argued for ultimately introducing ‘a limited legal cannabis market’ accompanied by ‘grudging tolerance’. Grudging tolerance would presumably need to include the same limiting measures I have advocated: taxation, strict regulation of cultivation and sale, health warnings, consumer quality controls and age restrictions on sale.

No policy is ever going to be perfect. But the introduction of cannabis taxation and regulation will surely be less costly to the community and less harmful to cannabis consumers than leaving the market to criminals and corrupt police.

A more detailed discussion with references is available here.