by Sujit Choudhry (ed). Cambridge, Cambridge University Press, 2007. 458pp. Hardback, £50.00/$90.00. ISBN: 9780521864824. eBook format. $72.00. ISBN: 9780511266829.

Reviewed by Carlo Guarnieri, Professor of Political Science, University of Bologna. Email: guarnica [at]


The migration of constitutional ideas across judicial systems has become one of the central features of contemporary constitutional practice. Two recent U.S. Supreme Court cases – LAWRENCE v. TEXAS (2003) and ROPER v. SIMMONS (2005), in which the Court majority quoted foreign sources in justifying its decision – have underlined the growing significance of the phenomenon. Aptly named, THE MIGRATION OF CONSTITUTIONAL IDEAS moves from the premise that there is a remarkable absence of serious reflection on this development: constitutional law seems out of step from a highly significant constitutional practice. Therefore, it presents a set of papers devoted to an analysis of the subject, originally prepared for a conference held at the University of Toronto in October 2004.

The general approach of the papers tries to move away from general theories of constitutional interpretation. As the editor – Sujit Choudhry – points out in his introductory essay, the book presents a bottom-up effort to analyze the reasons offered by courts and other legal actors for the recourse to comparative materials and to weave those justifications into coherent accounts. The final aim is to build constitutional theories in order to explain and, above all, justify interpretive practices.

As Choudhry notes, migration seems to be a better metaphor to describe what is really going on in the constitutional landscape of many countries. In fact, legal transplants – a term often used by constitutional scholars – could only occur if the rule and its context could be transferred between legal systems without any alteration, a very unlikely prospect, since a legal rule is likely to be understood in a different way by the “host” culture, becoming in fact a different rule. As pointed out also by Kim Lane Scheppele in her contribution, another popular metaphor – that of constitutional borrowing – has its limits. Unlike what happens in reality, borrowing denotes ownership on the part of the lender and therefore the fact that ideas should be returned to the original jurisdiction, although it is not always clear in what ways this can be done. Moreover, “borrowed” ideas should be used without significant modification or adaptation. In fact, the migration of constitutional ideas encompasses a much broader range of relationships between the recipient jurisdiction and constitutional ideas: as pointed out by Neil Walker, migration “presumes nothing about the attitudes of the givers or the recipient, or about the properties or fate of the legal objects transferred” (p.320).

The volume is divided into four parts. In the first, some basic methodological [*505] aspects of comparative analysis are addressed. Ran Hirschl, arguing from a comparative politics perspective, underlines the lack of reliable explanations of constitutional migrations: “we still know precious little about the actual extent of this phenomenon, let alone why, when, and how such migration has been occurring or is likely to occur” (p.64). In fact, legal studies of comparative constitutionalism tend to lack sufficient methodological rigour, since they do not follow the principles – already recognized by contemporary social science – of controlled comparison, accurate research design and good case selection. Therefore, they have not been able to produce convincing explanations of constitutional migrations. On the other hand, comparative political scientists, working with more methodologically conscious approaches, have been able to explain to a large extent the related phenomenon of the recent spread of written constitutions and bills of rights.

Hirschl’s paper is the only real contribution from a social science perspective. All the remaining authors tend to argue mainly from a legal point of view, their principal goal being to justify or criticize the practice on the basis of some legal principle. Thus, Mark Tushnet reflects on the ways comparative constitutional law can improve the ability to make better domestic constitutional law, a goal he thinks can and should be achieved. As for the other contributions, a first theme centres on whether constitutional migrations have facilitated the emergence of a common constitutional model, with Lorraine Weinrib arguing for the emergence of a “post-war juridical paradigm” of rights protection – to whom the United States are in part foreign – and Jeffery Goldsworty, Michel Rosenfeld and Andràs Sajò suggesting that significant variations between countries continue to exist and that convergence should not be always considered a positive fact. On the other hand, writing from the privileged point of view of a mixed legal system like Canada, Jean-François Gaudreault-Desbiens asserts that the post-Second World War constitutional model has led to a sort of migration of interpretive methodology from the civil law to the common law. As for the question if and to what extent these developments have – or not – involved the USA, Lorraine Weinrib and Brenda Cossman give partially different answers.

Another part of the volume is devoted to the influence of international and transnational – e.g. European Union – law on national jurisdictions. Mayo Moran and Mattias Kumm assess the legitimacy of importing constitutional ideas from international law from within the standpoint of domestic constitutional law. Moran, on the basis of British, Canadian and South African cases, finds that the values of international and comparative law influence domestic constitutional law and, in turn, the values of constitutional law influence domestic private law. Kumm, in his analysis of the jurisprudence of the European Court of Justice and of the European Court of Human Rights, arrives at similar conclusions on the influence of constitutional ideas from international law and presents “a framework for thinking about the moral concerns that [*506] any set of doctrines governing the interface between national and international law ought to take into account and reflect” (p.261). David Schneidermann and Neil Walker ask whether the conceptual lens of domestic constitutionalism has migrated and should migrate to the international level in order to become a standard for transnational governance and give partially different answers: on the whole positive by Schneidermann, while Walker points out the complexities involved in the EU case.

Finally, a set of papers tries to assess the most recent cases of migration of constitutional ideas, those in the wake of 9/11. Here, the comparative conversation between different judicial and legal systems seems strong, but the judgments on their merits are diverse. Scheppele points out that migration is not always a good thing, as it has been the case with anti-constitutional ideas inserted in the legislation on emergency powers enacted as a consequence of UN Security Council resolutions against terrorism. Similarly, Oren Gross underlines the risk that anti-constitutional ideas migrate from the periphery to the centre, as in the case of emergency regimes applied in colonies – as in Algeria by France – or in dependent territories, as in Northern Ireland by Britain. On the other hand, in his analysis of the drafting of anti-terrorism legislation in Australia, Canada, Hong Kong, Indonesia, South Africa, United Kingdom and United States, Kent Roach points out the filtering effect played by national jurisdictions against the migration of anti-constitutional ideas.

Migration of legal ideas is by no means a new phenomenon. The entire history of private law has been characterized by migrations. Also public law is not foreign to similar developments, as shown by the influence exerted on many countries of continental Europe and Latin America by Napoleonic reforms of the organization of criminal procedure (Merryman 1985) or by the recent spread in many civil countries of more or less accusatorial, American-style codes of criminal procedure (Langer 2004). As for constitutional law, the influence of some constitutions – like the constitutions of the United States, of Federal Germany or of the French Fifth Republic – on constitution-drafting is well-known.

What is really new today is the accelerated rate according to which legal and constitutional ideas migrate from one judicial system to another. Above all, the most significant development is the crucial role played by judges in the process of migration. As many of the contributions in the book underline, in most cases judges are those actually giving effect to the influence of migrating constitutional ideas. One of the results of this trend is that judicial creativity and power come out magnified, making even more acute the “democratic deficit” of the judiciary. Moreover, the expanded role of foreign jurisprudence does further the decline of the sovereignty of the State, a basic principle of the modern, “Westphalian” State, triggering an adverse reaction in those political contexts in which the principle still enjoys rather strong support (as in the United States, for example). [*507]

The book provides a careful and well-diversified analysis of all these developments. However, as underlined by Hirschl, convincing explanations are lacking. Almost all the contributors devote their analyses to the evolution of jurisprudence and legislation, but do not deal with the problem of the actual reasons behind the increasing significance of constitutional migration. A partial exception is Jeffery Goldsworty. Noting that the increasing support for a stronger role of the judicial branch is related to “the contemporary loss of faith in the old democratic ideal of government by ordinary people” (p.121), he looks for an explanation and suggests it lies in the fact that, at least in some countries, “a substantial number of influential members of the highly educated, professional, upper-middle class have lost faith in the ability of their fellow citizens to form opinions about important matters of public policy in a sufficiently intelligent, well-informed, dispassionated, impartial, and carefully reasoned manner” (p.122). In this situation, strengthening judicial power means shifting power to people who are often representative members of that very class. It is interesting to note that this suggestion can be easily made compatible with the broader analysis put forward by Hirschl on the role played in supporting the expansion of judicial power by “hegemonic groups,” fearful of losing their grip on political power (Hirschl 2004). In fact, when considering constitutional developments, we should always take into account the interests involved in the process and, in this case, their capacity of developing good relationships with the legal professions – and the judiciary – and of introducing institutional changes conducive to stronger judicial power. Obviously, the picture is extremely complex and should be adjusted to the different characters of the legal and political systems, deserving a long term research strategy and collaboration between legal scholars and political scientists. This is the main reason why the book, although presenting mainly a legal point of view, is an important contribution to this effort.


Langer, Màximo. 2004. “From Legal Transplants to Legal Translations: The Globalization of Plea Bargaining and the Americanization Thesis in Criminal Procedure”, 45 HARVARD INTERNATIONAL LAW JOURNAL 1-64.

Merryman, John Henry. 1985. THE CIVIL LAW TRADITION. Stanford: Stanford University Press. (2nd edition).

LAWRENCE v. TEXAS, 539 US 558 (2003).

ROPER v. SIMMONS, 543 US 551 (2005).

© Copyright 2007 by the author, Carlo Guarnieri.