The principle that decisions on policy should be taken at the most decentralized level consistent with making them effective. Decisions affecting the global atmosphere, for example restrictions on the use of CFCs, need to be taken at an international level. Decisions on safety standards for vehicles need to be taken at at a national or possibly supranational level. There is a tendency in modern economies for an increasing proportion of policy decisions to be centralized, from local authorities to national governments, and from national governments to supra-national bodies such as the European Union (EU). The main arguments for subsidiarity are first, that there are so many decisions to be taken that the centre should not be swamped in detail; and second, that there are national and local variations in income levels, traditions, and social attitudes, so that common rules which were hardly noticed in one area, where they merely formalise established habits, would be regarded as so outrageous as to be unenforceable in others.

• domestic distortions
• domestic product
• domestic rates
• dominant firm
• dominant strategy
• domino effect
• dotcom company
• double counting
• double entry bookkeeping
• double taxation
• double taxation agreement
• Douglas
• Dow Jones Industrial Average
• down payment
• downside risk
• downstream
• downward-sloping demand curve
• draft, banker's
• drag, fiscal
• drawback, customs
• drawing rights
• dual economy
• duality
• dummy variable
• dumping