month use by 4 to 5 percent. Using Monitoring the Future survey data for 1982 and 1989, Chaloupka et al. (1998) estimated that decriminalizing marijuana in all states would raise the number of youths using marijuana in a given year by 4 to 5 percent compared with the number using it when marijuana use is criminalized in all states; however, they also found no relationship between decriminalization and past-month use or frequency of use.
It is worth emphasizing that any prediction of increased use after a reduction or elimination of penalties against users depends on awareness of the decriminalized status of the behavior. Although laws decriminalizing marijuana use typically received a great deal of publicity when they were adopted, it appears that most people in these states no longer have the impression that marijuana penalties in their states are distinctively different from marijuana penalties in other states (MacCoun and Reuter, 2001). In the absence of a salient and persistent impression that penalties for marijuana use are distinctly more lenient than penalties in other states, one would not expect prevalence of marijuana use to differ significantly in the decriminalized jurisdiction when compared with neighboring jurisdictions.
In summary, existing research seems to indicate that there is little apparent relationship between severity of sanctions prescribed for drug use and prevalence or frequency of use, and that perceived legal risk explains very little in the variance of individual drug use. However, there are many gaps in current knowledge concerning the declarative and deterrent effects of prescribing and enforcing penalties for drug possession. Studies thus far conducted have been limited in several ways.
First, existing research uniformly focuses on the effect of prescribed penalties. However, sanctions prescribed by statute do no more than set the outer boundary within which highly selective judgments are made by police, prosecutors, and judges. Virtually nothing is known about the deterrent impact of variations in enforcement on drug use or about the conditions under which deterrence can be increased. Second, deterrence studies typically rely on general population surveys to provide measures of undeterred drug use. However, the actual probability that sanctions will be imposed on violators differs widely across demographic groups, and it has been repeatedly demonstrated that persons arrested and punished for using drugs differ significantly from the population of users (Husak, 1992; Kleiman and Smith, 1992; Zimring and Hawkins, 1992; Tonry, 1995).
Third, very few studies have included the use of opiates or cocaine as the dependent variable. Most have tested the deterrent effects of punishment and social control on alcohol or marijuana use, drunk driving, or other crimes that have higher base rates (e.g., Meier and Johnson, 1977;