On the Optimal Specificity of Legal Rules
European lawmakers are undertaking important steps towards the harmonization, unification, and possible codification of some areas of European private law. In doing so they can choose to craft laws with different levels of detail to guide judges in their decision-making process, incorporating rules or standards into the laws they write. The optimal degree of specificity of legal rules under different environmental conditions and the functionality of these rules or standards are the subject of the present study. First, a basic model of optimal specificity of laws is presented, clarifying the relevance of legal obsolescence and volume of litigation in the optimal choice. We further consider the important influence of codification style, judges' specialization, and complexity of reality on the optimal choice of legislative instrument. The results shed some light on the historical patterns of legislation in various areas of the law, and provide some policy recommendations for the ongoing process of codification in the European context.