Almost every year, The Economist has a special edition where the issue of drug legalisation is raised. The perspectives, examples and arguments vary, but the underlying line is the same: the war on drugs is not over and is bloodier than ever.

Even British Deputy Prime Minister Nick Clegg has, in a number of high-profile statements, responded favourably to a change in drug policy. There are a number of parallel changes. Some countries have begun to adopt new methods of treatment for addicts, in others, such as Portugal and the Czech Republic, a new approach has been taken regarding the possession and consumption of drugs.

Another perspective shift that has taken place over the past decade is that drug policy can no longer be considered only from a nation-state perspective. Just as no country has a unilateral trade policy, more countries have come to understand that drug policy in one country very much influences events in another. This ...