This chapter investigates the problem of how the transplant and borrowing of foreign constitutional law and international law can influence constitution- making processes and constitutional interpretation – state actions which are still considered sovereign. International law, especially international human rights laws, are of preeminent importance in this context since they are virtually by definition based on limitations on national constitutional law to assert internationally shared constitutional principles. In other words, the chapter seeks to answer the question of how far the process of the internationalization of (national) constitutional law has progressed; to what extent are the framers of constitutions and the courts that interpret constitutions willing to accept alien, foreign, or international principles and rules? What underlies the decision by the constitutional organs of certain states to accede to such constitutional migration, and the rejection of such migration by their respective counterparts in other countries?

A growing constitutional cross- fertilization is taking place between national constitutional systems. This process may contribute not only to the emergence of better constitutions and improved (constitutional) court decisions, but also to the rise of a ‘global legal system’. 1 Ultimately, the globalization of constitutional law implies that constitutionalism is no longer the sole prerogative of nation- states, but emerges instead as a set of standards for an international community that is now in the process of taking shape. 2 This internationalization is bolstered especially by the expansion of commercial ties and communication, and the increasing depth of political, economic, cultural and legal relations. In certain analyses they emphasize the potential effects of globalization via market processes on constitutional rights. 3 As economic globalization also implies rivalry – for investments and labour – between states, however, internationalization is primarily limited to countries that partake in the international competition for capital and labour; 4 and at least those among the latter segment that use international models for designing, amending or interpreting their constitutions. Also, modern computer technology, personal connection between justices, and developments in legal education have made the circulation of case law easier and more frequent. 5

To illustrate the various ways in which comparative law materials are used, academic literature frequently turns to the use of metaphors. One of these is the so- called legal transplant, which designates the translation of rules between legal systems. In his early work Alan Watson argued that he needed to address the transplantation of the science of comparative law. 6 Watson himself has been careful to note that his conclusions were properly applicable to the development of private law. Christopher Osakwe is even more certain that public law, much more than private law, is infused with indigenous political, social and economic realities, and therefore is closely linked to national traditions. 7 In his critique of Watson, Pierre Legrand claims that transplantation is not a viable enterprise; in rejecting convergence he emphasizes differences. 8 Csaba Varga reports on the role that transplantation played during the Hungarian regime transition, 9 while Angelika Nussberger on the transfer of constitutional law from West to East. 10

Another metaphor employed is the opposite of the aforementioned, namely constitutional borrowing. 11 Those who employ the metaphor of the ‘migration’ of constitutional ideals argue that that is the only concept capable of capturing the versatile impact of constitutional ideals on the judicial practices that incorporate them, as well as to express both constitutional differences and the commitment to a comparative approach, though the latter does not necessarily imply the assertion that constitutions and judicial practices converge. 12 In another study Sujit Choudhry uses the term ‘dialogical interpretation’ in the context of constitutional interpretation, which falls outside the scope of ‘constitutional borrowing’, but is within the scope of the ‘migration’ of constitutional principles. 13 This model of comparative constitutional law interpretation bears similarities to Vicki C. Jackson’s ‘engagement’ model, 14 as well as to Sarah K. Harding’s model, which is also based on ‘dialogue’. 15 The political scientist, Ran Hirschl argues that the question, why is the migration of constitutional migration happening cannot be answered by a juristic methodology or by legal argumentation alone. Therefore, he suggests to turn from comparative constitutional law to comparative constitutional studies. 16

The migration of constitutional ideals may manifest itself in the use of foreign constitutional solutions, in the process of drafting constitutions, as well as in the application of comparative law in construing constitutions. This is the context in which Frederick Schauer distinguishes between imposed, transplanted, indigenous and transnational constitutions. 17 Addressing these important manifestations of constitutional migration must begin by addressing the preliminary theoretical question of how far the sovereignty of the branches of powers that make and interpret constitutions, respectively, extend in terms of applying external constitutional solutions or completely disregarding them.

Rosalind Dixon and Eric A. Posner describe four paths to constitutional convergence. 18 The first one is represented by superstructure theories, which argue that constitutions refl ect deeper forces – technological, demographic, economic – and therefore constitutions converge across countries just when those factors converge. 19 This means that constitutional borrowing is not within the direct control of constitution- makers, while the other three mechanisms assume that decision- makers do control constitutional change. One means of borrowing is via learning theories, which argue that judges, political actors who produce constitutional norms copy what they see in other legal orders, mostly using of course the more successful or older counties’ solutions, as it happened with the postcommunist countries, like Hungary after the transitions in 1989– 1990, using many German constitutional approaches. The next theory is of coercion, which argues that countries try to compel other countries to use their constitutional norms. From a different point view one can state that the countries of East- Central Europe after becoming democratic, believed that they have no choice but to adopt liberal democratic constitutions, if they were have a chance at attracting global trade and investment. Finally , competition theories argue that countries change their norms to attract migration, or trade, and this should also lead to constitutional convergence. Assessing these theories, Dixon and Posner conclude that probably the best case for constitutional convergence comes from the superstructural approach. 20

1 This possibility is proposed by A.- M. Slaughter , A New World Order , (Princeton University
Press , 2004), 65 – 103 .
2 Bruce Ackerman has already envisioned this future towards the end of the 1990s. See B.
Ackerman , ‘ The Rise of World Constitutionalism ’ (1997) 87 Virginia Law Review 771 .
3 Cf. D. S. Law , ‘ Globalization and the Future of Constitutional Rights ’ (2008) 102
Northwestern University Law Review 1277 , and especially 1280 .
4 See M. Tushnet , ‘ The Inevitable Globalization of Constitutional Law ’ (2009) 49 Virginia
Journal of International Law 985 – 1006 .
5 See T. Groppi and M.- C. Ponthoreau , ‘ Introduction. The Methodology of Research: How to
Assess the Reality of Transjudicial Communication? ’, in T. Groppi and M.- C. Ponthoreau
(eds.), The Use of Foreign Precedents by Constitutional Judges, (Hart Publishing , 2013 ), 7 .
6 See A. Watson , Legal Transplants: An Approach to Comparative Law ( Scottish Academic
Press , ( 1974) .
7 See C. Osakwe , ‘ Introduction: The Problems of Compatibility of Notions in Constitutional
Law ’ ( 1984 ) 59 Tulane Law Review 875 , 876 .
8 Cf. P. Legrand , ‘ What “Legal Transplants” ’, in D. Nelken and J. Feest (eds.), Adapting Legal
Cultures ( Hart Publishing , 2001 ).
9 See C. Varga , ‘ Transfer of Law. A Conceptual Analysis ’, in Hungary’s Legal Assistance.
Experience in the Age of Globalization ( Nagoya , 2006 ).
10 See A. Nussberger , ‘ Verfassungstransfer von West nach Ost: Illusion, Desillusion,
Neubeginn ’ ( Osteuropa , 2010) , 81 – 96 .
11 See the published materials of the scientifi c symposium on ‘constitutional borrowing’:
( 2003 ) 1 International Journal of Constitutional Law 177– 324.
12 On the metaphors see S. Choudhry , ‘ Migration As a New Metaphor in Comparative
Constitutional Law ’, in S. Choudhry (ed.), Migration of Constitutional Ideas ( Cambridge
University Press , 2006 ).
13 See S. Choudhry , ‘ Globalization in Search of Justifi cation: Toward a Theory of Comparative
Constitutional Interpretation ’ (1999) 74 Indiana Law Journal 819 , 835 .
14 See V. Jackson , Constitutional Engagement in a Transnational Era ( Oxford University
Press , 2010 ).
15 See S.K. Harding , ‘ Comparative Reasoning and Judicial Review ’ ( 2003 ) 28 The Yale
Journal of International Law 409 – 467 .
16 Cf. R. Hirsch , Comparative Matters ( Oxford University Press , 2014 ), 281 . In contrast to
Hirschl’s social scientifi c approach, Armin von Bogdandy in his critique of the book
favours a more lawyerly approach. See A. v. Bogdandy , ‘ Comparative Constitutional Law
as a Social Science? A Hegelian Reaction to Ran Hirschl’s Comparative Matters ’ ( 2016) 49
VR Ü Verfassung und Recht in Ü bersee 278 – 290 .
17 See F. Schauer , ‘ On the Migration of Constitutional Ideas ’ (2005 ) 37 Connecticut Law
Review 907 .
18 See R. Dixon and E. Posner , ‘ The Limits of Constitutional Convergence ’ ( 2011 ) 11 2 Chicago
Journal of International Law 400 .
19 The scholars representing this theory are writing in economic and political science literature,
treating constitutions as endogenous, like the work of D. Acemoglu and J.A.
Robinson , Economic Origins of Dictatorship and Democracy ( Cambridge University Press ,
2006 ). Cited by Dixon and Posner, id., on p. 408.
20 Cf. Dixon and Posner, id., at 421.