The first section explains the historical evolution of drug laws and drug use in France, Great Britain, Italy, the Netherlands, and Switzerland. It also studies the interaction between criminal justice measures and public health measures in the fight against drugs. In this context it shows an array of shifting priorities (e.g., health concerns, concerns about public order) and factors of influence (e.g., public opinion, the cost of drug repression) which determine policymaking. In evaluating these complex and vacillating national policies, a study would have to resolve numerous methodical difficulties. The preliminary framework established in this document suggests the following principles for an evaluation. First, an in-depth study of small comparable user populations would be preferable to the comparison of entire countries. Second, the effects of a drug policy should be evaluated by the circumstances in which drug users use their drugs rather than by the number of users. Third, the study should approach drug use as a problem of public health rather than public order. Last, the evaluation should also consider the effects of policymaking on the general population. 45 references