The Expressive Function of Proportionality. The study of difference in the use of proportionality unveils certain core characteristics of the legal cultures that embrace it. As proportionality spreads in different jurisdictions its meaning changes to adapt to local criteria for evaluating legal arguments and to local actors’ expectations of its use. It assumes a function that is sometimes very different from the one it has in the global model or in German constitutionalism. Proportionality becomes a French legal theory claiming scientific exactness, a tool for the construction of an English public law or a transplant for the Europeanisation of the Greek polity. The different meanings of proportionality in different contexts make sense, at least in part, of differences in its form and evolution observed in Part I. Indeed, even though German and European influence is present in the conceptual development of proportionality in all contexts, it is not decisive for the content that proportionality will assume each time. In spite of using elements of a transnational idiom, local actors serve their own goals, which are conceived of and set within a particular culture. Hence, proportionality, precisely due to its transnational character, acquires an expressive function. The way its meaning, form and function vary across jurisdictions despite the commonality of the terminology used, reveals the peculiar logic of local legal discourses. It reveals local ways of thinking, taboos and myths, expectations and ambitions. It also reveals local patterns of legal change.