The increased enforcement of criminal marijuana prohibition has failed to reduce marijuana use and access in the United States, according to a report released today by the International Centre for Science in Drug Policy.

The report — based almost entirely on published U.S. government data — finds that increased funding for marijuana law enforcement is not associated any demonstrable reduction in marijuana availability, arrests, potency, or “rates of cannabis-related harm.”

The following excepts are taken from the report’s executive summary and conclusion.

Tools for Debate: US Federal Government Data on Cannabis Prohibition

A report of the International Centre for Science in Drug Policy

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.

… Given that cannabis prohibition has clearly failed to achieve its stated objectives and has also resulted in a range of serious unintended harms, regulatory models should be given urgent consideration, both in the United States and in other settings. … In light of the widespread and often free availability of cannabis that exists despite extremely costly criminal justice measures, successfully reducing rates of cannabis-related 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.