On the one hand, there are the physiological and psychosocial costs of marijuana use: undesirable personality changes, antisocial behavior patterns, alterations in properly coordinated motor activity, psychological dependence liabilities, and the undetermined spectrum of health consequences from the drug's long-term chronic use. The prevention of these effects could be considered the benefits of criminalization policies if existing marijuana statutes were indeed effective in deterring those who might otherwise use the drug. By contrast, there are personal, social, and economic costs related to the implementation of current marijuana laws. These include the personal costs of temporary, long-term, or even permanent disruption in users' lives which result from arrest, conviction, sentencing, and incarceration. The social costs include society's loss of productive or potentially productive citizens through criminal justice intervention. The economic costs are the total budget allocations to the criminal justice system for the enforcement of marijuana laws and the processing and management of offenders. This conceptualization involves gathering data on the effects of marijuana use on current regular users compared to nonusers and multiple-drug users, controlling for such variables as age at onset of use, frequency of use and intoxication, settings of use and intoxication, and intellectual and motor performance. Other areas for research include the impact of arrest and conviction on cohorts of marijuana users, the economic costs of enforcing the marijuana laws, the benefits of marijuana as a substitute for consumption of more dangerous drugs, and public attitudes and conceptions regarding marijuana use. Tabular data on marijuana arrests are provided along with eight notes.