This evidence is consistent with the idea that appellate judges' offsetting biases make common law unbiased but volatile and thus more efficient than the certain civil law only when the latter is sufficiently distorted by the lobbying activities of special interests, i.e., when preferences are sufficiently heterogeneous and/or the political process sufficiently inefficient (Guerriero, 2016a). These results cast several doubts on the putative primacy of common law and suggest that comparative law and economics should not only take into account the evolving nature of legal traditions and their endogeneity to preference diversity and the quality of political institutions, but also the nature of the performance of interest. Guerriero (2016b) shows that properly considering these points delivers conclusions very different from those drawn by La Porta et al. (2008).