The “comparative quality” of common law and civil law has become an issue of policy, since La Porta, Lopes-de-Silanes, Shleifer and Vishny (LLSV) developed their “legal origins theory” (LOT) asserting that common law countries enjoy better governance and economic performance than civil law countries. Influencing the methodology of the “Doing Business” Reports of the World Bank and the country analyses of rating agencies, LOT affects the creditworthiness of transforming and developing countries and hence casts doubt on assistance to legal reforms in these countries from civil law sources. This introductory chapter proposes a map of the methodological issues that are raised in terms of theory and policy. Reviewing LOT’s methodology requires meeting LLSV in the interdisciplinary arena of political theory, sociology and economics, which they have chosen, while extending it to the disciplines of institutional economics, comparative law, legal history and philosophy of science, which they have neglected.