Abstract: The global war on drugs is driving the HIV/AIDS pandemic among people who use drugs and their sexual partners. Throughout the world, research has consistently shown that repressive drug law enforcement practices force drug users away from public health services and into hidden environments where HIV risk becomes markedly elevated. Mass incarceration of non-violent drug offenders also plays a major role in increasing HIV risk. This is a critical public health issue in many countries, including the United States, where as many as 25 percent of Americans infected with HIV may pass through correctional facilities annually, and where disproportionate incarceration rates are among the key reasons for markedly higher HIV rates among African Americans. Aggressive law enforcement practices targeting drug users have also been proven to create barriers to HIV treatment. Despite the evidence that treatment of HIV infection dramatically reduces the risk of HIV transmission by infected individuals, the public health implications of HIV treatment disruptions resulting from drug law enforcement tactics have not been appropriately recognized as a major impediment to efforts to control the global HIV/AIDS pandemic. The war on drugs has also led to a policy distortion whereby evidence-based addiction treatment and public health measures have been downplayed or ignored. While this is a common problem internationally, a number of specific countries, including the US, Russia and Thailand, ignore scientific evidence and World Health Organization recommendations and resist the implementation of evidence-based HIV prevention programs – with devastating consequences. In Russia, for example, approximately one in one hundred adults is now infected with HIV. In contrast, countries that have adopted evidence-based addiction treatment and public health measures have seen their HIV epidemics among people who use drugs – as well as rates of injecting drug use – dramatically decline. Clear consensus guidelines exist for achieving this success, but HIV prevention tools have been under-utilized while harmful drug war policies have been slow to change. This may be a result of the mistaken assumption that drug seizures, arrests, criminal convictions and other commonly reported indices of drug law enforcement “success” have been effective overall in reducing illegal drug availability. However, data from the United Nations Office on Drugs and Crime demonstrate that the worldwide supply of illicit opiates, such as heroin, has increased by more than 380 percent in recent decades, from 1000 metric tons in 1980 to more than 4800 metric tons in 2010. This increase coincided with a 79 percent decrease in the price of heroin in Europe between 1990 and 2009. Similar evidence of the drug war’s failure to control drug supply is apparent when US drug surveillance data are scrutinized. For instance, despite a greater than 600 percent increase in the US federal anti-drug budget since the early 1980s, the price of heroin in the US has decreased by approximately 80 percent during this period, and heroin purity has increased by more than 900 percent. A similar pattern of falling drug prices and increasing drug potency is seen in US drug surveillance data for other commonly used drugs, including cocaine and cannabis. As was the case with the US prohibition of alcohol in the 1920s, the global prohibition of drugs now fuels drug market violence around the world. For instance, it is estimated that more than 50,000 individuals have been killed since a 2006 military escalation against drug cartels by Mexican government forces. While supporters of aggressive drug law enforcement strategies might assume that this degree of bloodshed would disrupt the drug market’s ability to produce and distribute illegal drugs, recent estimates suggest that Mexican heroin production has increased by more than 340 percent since 2004. With the HIV epidemic growing in regions and countries where it is largely driven by injection drug use, and with recent evidence that infections related to injection drug use are now increasing in other regions, including sub-Saharan Africa, the time for leadership is now. Unfortunately, national and United Nations public health agencies have been sidelined. While the war on drugs has been fueling the HIV epidemic in many regions, other law enforcement bodies and UN agencies have been actively pursuing an aggressive drug law enforcement agenda at the expense of public health. Any sober assessment of the impacts of the war on drugs would conclude that many national and international organizations tasked with reducing the drug problem have actually contributed to a worsening of community health and safety. This must change.