No one doubts the damage done by widespread drug addiction, both to its victims and in funding organised crime.

The World Drug Report 2007, compiled by the United Nations Office on Drugs & Crime, contains the results of sample surveys on the prevalence of the use of opiates, cocaine, cannabis, ecstasy and amphetamines. We combined these in one index, giving them equal weights, and found a strong tendency for drug abuse to be more common in more unequal countries.

Among the 50 states of the USA drug addiction and deaths from drug overdoses are related to inequality. Again we found that the more unequal states had higher death rates.