The first major decision that the committee made was to focus on substances whose sale or use is illegal in America today, taking the legal status of drugs as given. A more expansive scope for our work could easily have been justified. From a public health perspective, addiction to such legal substances as tobacco and alcohol may constitute problems more severe in their adverse consequences than addiction to such illegal drugs as cocaine, heroin, or marijuana. From a behavioral perspective, complementaries in the use of legal and illegal drugs have been conjectured in the “gateway hypothesis,” which posits that the early use of tobacco and marijuana is usually a precursor to the use of hard drugs, while the substitutability of legal and illegal psychoactive drugs has been emphasized by economic models that focus on the role of prices in determining drug use. From a legal perspective, it is useful to keep in mind that the legal status of addictive substances is not immutable; drug laws are made by and can be changed by society.
All of these considerations notwithstanding, the committee made a pragmatic decision to focus its attention on the illegal drugs that are the targets of present-day drug control policy. We decided that any attempt to confront the public health problems posed by alcohol and tobacco would make the task entirely unmanageable. We do, however, cite data and research on alcohol and tobacco when they may offer lessons for analysis of illegal drugs, for example, when studying the drug use of minors. We decided that changes in the legal status of addictive substances, such as the prohibition of alcohol and the legalization of marijuana, are not sufficiently under active consideration by policy makers for this committee to contemplate what data and research may have to say about these policy options.
Indeed, the committee has for the most part focused on a subset of illegal drugs. This report dwells on cocaine, with lesser attention to heroin, and still less to other drugs. Giving primacy to cocaine may be natural in light of the “crack” cocaine crisis that gripped American society in the 1980s and the continuing position of cocaine as a focus of research and a flash point in the public debate about drugs. Yet the committee is aware that patterns of drug use may change with time. Twenty years ago it would have been natural to give primacy to heroin, and this may again be the case in the near future. Or one of numerous synthetic addictive substances may pose the overriding drug threat of tomorrow. Be this as it may, the broad substantive concerns and methodological issues addressed in this report will remain germane to drug policy.