The dynamics by which norms emerge and spread in international society have been the subject of strikingly little study. This article focuses on norms that prohibit, both in international law and in the domestic criminal laws of states, the involvement of state and nonstate actors in activities such as piracy, slavery, counterfeiting, drug trafficking, the hijacking of aircraft, and the killing of endangered animal species. It analyzes the manner in which these norms have evolved into and been institutionalized by global prohibition regimes and argues that there are two principal inducements to the formation and promotion of such regimes. The first is the inadequacy of unilateral and bilateral law enforcement measures in the face of criminal activities that transcend national borders. The second is the role of moral and emotional factors related to neither political nor economic advantage but instead involving religious beliefs, humanitarian sentiments, fears, prejudices, paternalism, faith in universalism, the individual conscience, and the compulsion to proselytize. The ultimate success or failure of an international regime in effectively suppressing a particular activity depends, however, not only on the degree of commitment to its norms or the extent of resources devoted to carrying out its goals but also on the vulnerability of the activity to its enforcement measures.

"Drug legalization" increasingly merits serious consideration as both an analytical model and a policy option for addressing the "drug problem." Criminal justice approaches to the drug problem have proven limited in their capacity to curtail drug abuse. They also have proven increasingly costly and counterproductive. Drug legalization policies that are wisely implemented can minimize the risks of legalization, dramatically reduce the costs of current policies, and directly address the problems of drug abuse.

Harm reduction policies and attitudes in the United States have advanced substantially in recent years but still lag behind more advanced jurisdictions in Europe and elsewhere. The Obama administration, particularly in its last years, embraced some harm reduction policies that had been rejected by previous administrations but shied away from more cutting edge interventions like supervised consumption sites and heroin-assisted treatment. The Trump administration will undermine some of the progress made to date but significant state and local control over drug policies in the US, as well as growing Republican support for pragmatic drug policies, motivated in part by the opioid crisis, ensures continuing progress for harm reduction.