Aims Decisions on whether and how to ‘schedule’ drugs (i.e. to determine their legal status and penalties to be applied for sale or possession) are often heavily criticized. We sought to assess more comprehensively the results of such decisions for newly emerging drugs.
Methods Through analysis of legislation and secondary sources, we identified 63 substances that have emerged since 1971, including all that have been added to the most restrictive schedule by the United Nations, United States, United Kingdom, Canada, Australia and/or New Zealand.
Measurements For each jurisdiction we recorded whether, when, and how the substance was scheduled and note what decisions engendered substantial criticism or controversy within the international treaties' framework of balancing medical benefits with risk of abuse.
Findings (i) The rate of emergence of new drugs has been fairly steady. (ii) There is broad cross-national agreement on what should be scheduled. (iii) The United States often acts first. (iv) Temporary bans that delay final decisions by 12–18 months can sometimes allow final decisions to be grounded on a substantially expanded research base. (v) It appears that no more than seven of the decisions reached by the United States with respect to the 63 substances are candidates for being considered errors, and arguably the United States has committed at most one serious Type I and one serious Type II error. Results for other countries are broadly similar.
Conclusions The process for determining the legal status of new psychoactive substances appears to function reasonably well, within the framework of international treaty obligations. Most criticisms relate to one or a few substances (e.g. 3,4-methylenedioxymethamphetamine) and/or complaints that the decisions discount benefits that are not recognized by the treaties (e.g. recreational or religious use).