To many, it seems obvious that reducing the supply of drugs offers an important way to control the drug problem. If there were no drugs to use, there would be no problem. If lesser quantities of drugs reached consumers in the United States, the problem would be diminished. If drugs were harder to find, or riskier to obtain, or simply more expensive, some potential users might be discouraged from starting, and some current users might seek treatment or abandon their use.

In this chapter, we concentrate on enforcement and other policy instruments that aim to reduce drug supply. We discuss the problems of measuring or otherwise estimating the effectiveness of supply-reduction efforts, assess current knowledge of retail drug markets, explain why an understanding of these markets is important for supply-reduction policy, and assess knowledge of the extent to which arrested drug dealers may be replaced by others. Enforcement efforts directed at drug users are examined in Chapter 6.

The belief that reducing the supply of drugs can help to control the drug problem is but one concern that drives the public commitment to enforcing the drug laws. In addition, the public enthusiasm for enforcement, including imprisonment of offenders, is supported by the view that