This chapter provides a comparative study of the application of proportionality by English and Greek judges in the field of EC market freedoms. It shows that both English and Greek judges have assumed their mission of juges communautaires de droit commun. Despite this appearance of convergence, I argue, the reception of proportionality follows local patterns of cultural change and local knowledge practices, which affect local lawyers’ possibilities to resist to the process of European integration, as well as their capacity shape this process. Common law pragmatism has allowed English courts to frame normative conflicts between domestic and EC law. When proportionality and the effet utile of EC market freedoms entered into conflict with fundamental constitutional principles of the common law, English judges have occasionally objected to their application. By way of contrast, the perception of law as science has not allowed Greek lawyers to frame normative conflicts between domestic and EC law. Proportionality as a European science has engineered important constitutional change and has considerably compromised the normativity of the Greek Constitution.