The report reviews 20 years of data from US government funded surveillance systems on government drug control spending, cannabis seizures and cannabis arrests, in order to assess the impact of enforced cannabis prohibition on cannabis potency, price and availability. The report’s findings highlight the clear failure of cannabis prohibition efforts by showing that as the United States has dramatically scaled up drug law enforcement, cannabis potency has nevertheless increased, prices have dropped, and cannabis remains widely available.

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The report also outlines the evidence-base supporting the benefits of cannabis legalization and regulation. While California prepares to vote on the Regulate, Control and Tax Cannabis proposition (Prop. 19), the debate has focused primarily on the legalization of cannabis, and has lacked a strong scientific voice outlining how the state can adopt licensing and regulatory mechanisms to help reduce cannabis-related harms.

Fact sheet

EXECUTIVE SUMMARY

Several initiatives in the state of California, including Bill 2254 and the Regulate, Control and Tax Cannabis proposition, have fuelled the international discussion about the known impacts of cannabis prohibition and the potential impacts of a regulated (i.e., legal) market.

Surprisingly, to date, an impact assessment of cannabis prohibition based on data derived through US federal government surveillance systems has been largely absent from this debate. Drawing upon cannabis surveillance systems funded by the US government, this report summarizes information about the impacts of US cannabis prohibition on cannabis seizures and arrests. The report also tests the assumption that increased funding for the enforcement of cannabis prohibition and subsequent increased seizures and arrests reduce cannabis-related harms, by evaluating US federally funded surveillance systems examining cannabis potency, price, availability and rates of use.

In the last several decades there has been a remarkable increase in US federal and state funding for anti-drug efforts, with the annual overall federal anti-drug budget as reported by the US Office of National Drug Control Policy increasing by more than 600% (inflation adjusted), from approximately $1.5 billion in 1981 to more than $18 billion in 2002 (the last year the budget was consistently reported).* While only a portion of this budget funded programs specific to cannabis prohibition, increased federal and state funding nevertheless coincided with a greater than 150% increase in cannabis-related arrests and a greater than 420% increase in cannabis-related seizures between 1990 and 2006.

The limitations of cannabis prohibition in the US, however, are demonstrated by federally funded surveillance systems which show an approximate increase of 145% in estimated cannabis delta-9-tetrahydrocannabinol (THC) content between 1990 and 2007, despite the dramatic increase in funding to anti-drug efforts. Furthermore, evidence of prohibition’s failure to reduce the supply of cannabis is demonstrated by the estimated decrease of approximately 58% (inflation adjusted) in the retail price of US cannabis between 1990 and 2007.

The limitations of US cannabis prohibition are further evidenced by the ease with which American youth report being able to obtain the drug. According to US drug use surveillance systems funded by the US National Institutes on Drug Abuse, over the last 30 years of cannabis prohibition the drug has remained “almost universally available to American 12th graders,” with approximately 80–90% saying the drug is “very easy” or “fairly easy” to obtain. The failure of prohibition to reduce cannabis supply is also demonstrated by the fact that roughly 60% of school-aged US youth who use cannabis report having obtained their most recently used cannabis for free or having shared someone else’s. Interestingly, rates of cannabis use among American youth do not inversely correlate with levels of funding for cannabis prohibition. Instead, the estimated annual prevalence of cannabis use among US grade 12 students rose from 27% in 1990 to 32% in 2008, whereas among 19- to 28-year-olds it went from 26% in 1990 to 29% in 2008.

While it has been argued that rates of cannabis use would be higher if strict criminal penalties were not in place, this argument is inconsistent with available scientific evidence which indicates that patterns of drug law enforcement are not strongly correlated with rates of cannabis use. Nevertheless, theoretical models have suggested that, if enacted, the proposals in California could increase cannabis use, and this report also describes a range of evidence-based regulatory tools that should be given consideration in any locality debating cannabis legalization.

Increased funding for cannabis prohibition has increased cannabis seizures and arrests, but the assumption that this reduces cannabis potency, increases price or meaningfully reduces availability or use is inconsistent with surveillance data the US federal government itself collects. In light of the widespread and often free availability of cannabis that exists despite extremely costly criminal justice measures, successfully reducing rates of cannabisrelated harm will likely require the implementation of strict regulatory measures which are associated with reducing the harms of other legal substances and are too commonly underutilized in the areas of tobacco and alcohol control.