How Effective is Micro Harm Reduction in Reducing Macro Harm?

MacCoun (1996) distinguishes between micro and macro harm reduction and notes that reducing micro harm (harm per unit of use) may or may not reduce macro (aggregate) harm depending on its effect on use. We present a simple model that relates micro and macro harm through five parameters: price, quantity, elasticity of demand, elasticity of supply, and the social cost of drug use. Parameterizing the relationship for the US cocaine market in 1992 suggests that about 75% of the apparent benefit of reducing micro harm experienced by users would be offset by increases in use. This suggests that reducing micro harm experienced by users has merit but that reducing the costs drugs impose on non-users may merit greater attention, since reducing those costs carries no risk of being offset by increases in use.