Becker, Wilson, and many other analysts argue that punishment and stigmatization deter criminal behavior by making it costly for the perpetrator. Politicians and the mass media have highlighted crimes and drugs as the cause of many social problems, and have thereby stigmatized criminals and, in particular, drug users. Perhaps as a consequence of these arguments and stigmainducing activities, there has been a great increase in the USA in state and local law enforcement personnel (from 770 000 in 1992 to 951 000 in 2002), expenditures for incarceration (from US$ 100 per capita in 1991 to US$ 184 per capita in 2001), and arrests and imprisonments in the USA in recent decades (jail and prison inmates increased from 1.2 million in 1990 to 2.1 million in 2001). Much of this repressive effort has focused on the ‘War on Drugs’; arrests for drug possession in the United States increased from 540 800 in 1982 to 1 235 700 in 2002.

Punishment and stigmatization may have unanticipated effects on public health in general and on drug-related harm in particular. As injection is a more efficient means of taking drugs than intranasal use, a number of researchers have suggested that punishment and stigmatization might increase the pressures on non-injecting heroin users and perhaps cocaine users to take up injection druguse (and for injectors to continue injecting) through decreasing the supply of drugs or driving up their costs. Others have found that aggressive police tactics and/or stigmatization may lead injection drug users (IDUs) to engage in hurried injection behaviors, to share syringes more often, and/or to inject in high-risk environments and, in addition, to impede the creation or functioning of syringe exchange, drug treatment or other programs to improve users’ health.

This study investigated whether three measures of legal repressiveness in large US metropolitan areas were associated with the population prevalence of injection drug use and with HIV prevalence among IDUs.