Encyclopedia of Private International Law
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Encyclopedia of Private International Law

Edited by Jürgen Basedow, Giesela Rühl, Franco Ferrari and Pedro de Miguel Asensio

The role and character of Private International Law has changed tremendously over the past decades. With the steady increase of global and regional inter-connectedness the practical significance of the discipline has grown. Equally, so has the number of legislative activities on the national, international and, most importantly, the European level. With a world-class editor team, 500 content items and authorship from almost 200 of the world’s foremost scholars, the Encyclopedia of Private International Law is the definitive reference work in the field. 57 different countries are represented by authors who shed light on the current state of Private International Law around the globe, providing unique insights into the discipline and how it is affected by globalization and increased regional integration. The Encyclopedia consists of three inter-linked pillars, enhanced by sophisticated search and cross-linking functionality. The first pillar consists of A-Z coverage of the scope and substance of Private International Law in the form of 247 entries. The second pillar comprises detailed overviews of the Private International Law regimes of 80 countries. The third pillar presents valuable, and often unique, English language translations of the national codifications and Private International Law provisions of those countries. This invaluable combination represents a powerful research tool and an indispensable reference resource.
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Chapter U.4: Unilateralism

Stéphanie Francq

I. Definition and historical development

Unilateralism is a theory of private international law, which is often opposed to multilateralism. In order to identify the applicable law, multilateralism tends to localize the ‘seat’ of each legal relationship or situation, or in more contemporary terms, the legal system with which the situation presents the closest connection. Multilateralism thus allocates each legal relationship to a legal order via a multilateral conflict rule. Unilateralism, in contrast, proposes to resolve conflict of laws via the spatial scope of the substantive rules in conflict. From a unilateralist perspective, the question is whether the law commands its application to a specific situation. Unilateralism thus rests on the premise that the spatial scope of rules can be determined from their content or nature and that conflict of laws should be solved on this basis.

p. 1780Throughout history, unilateralism has taken various forms. It is commonly accepted that unilateralism was the method used to solve conflict of laws from the 12th century until the second part of the 19th century. The 19th century was marked by Savigny (→Savigny, Friedrich Carl von) ‘Copernican revolution’, but unilateralism never disappeared in Europe, or in the USA.

1. Statutist period – 12th to 19th centuries

The question of choice-of-law rules has arguably been identified since Italian cities gained relative independence within the Empire and started developing their own legal provisions (or statuta) in some areas. Early forms of globalization (→Globalization and private international law), materialized in international/inter-city commerce, as well as individuals travelling and migrating, forcing scholars and courts to consider the application of their own statutes or of those of other municipalities in situations that were not purely domestic. The first solutions were derived from Roman law and in particular from the Corpus Juris of Justinian and a passage thereof, well known under its first terms: Cunctos populos (Cunctos populos quos clementiae nostrae regit imperium, in tali sanctissima volumus religion versari, quam divinum Patrum apostolum tradidisse Romanis, stating in short that subjects of the Roman empire should embrace the Christian faith). A scholar called Karolus de Tocco, interpreting the lex cunctos populos, concluded that statutes are obligatory for those who are submitted to them or to the authority enacting them (‘Statutum non ligat nisi subditos’; Eduard Maurits Meijers, ‘L’histoire des principes fondamentaux du droit international privé à partir du Moyen Age spécialement dans l’Europe occidentale’ (1934) 49 Rec. des Cours 534, 594). From there, the ‘conflict’ of statute was envisioned as a process of identification of those who were submitted to a specific statute and thus of determination of the statute’s scope. The identification of the statute’s scope operated with reference to its nature or content and statutes were progressively classified in, more or less precise, categories according to their content and their corresponding reach. With the passing of time, the accumulation of case-law, the categories of statutes progressively gave rise to a ‘fairly coherent system of principles and rules’ restated by →Bartolus in the 14th century (Rodolfo de Nova, ‘Historical and Comparative Introduction to Conflict of Laws’ (1966) 118 Rec. des Cours 435, 446). A corresponding ‘French’ statutist school, in the meanwhile, had developed according to rather similar terms (Eduard Maurits Meijers, ‘L’histoire des principes fondamentaux du droit international privé à partir du Moyen Age spécialement dans l’Europe occidentale’ (1934) 49 Rec. des Cours 596–7), but it is the later version thereof that is usually referred to in literature, citing especially the work of d’Argentré (16th century). D’Argentré classified all the statutes in only two categories, according to their effect: statuta realia, the dominant category applying territorially, and statuta personalia, potentially applying extra-territorially. D’Argentré’s extensive conception of →territoriality was later received in Holland and inspired the three famous maxims of Ulrik Huber (→Huber, Ulrik). In 1689, Huber was the first to concentrate on conflicts between the laws of different states (Ulrich Huber, ‘De conflictu legum diversarum in diversis imperiis’ in Paelectiones juris romani et hodierni (1689, reproduced by Ernest G Lorenzen: Ernest G Lorenzen, ‘Huber’s De Conflictu Legum’ (1919) 13 Illinois Law Review 375)) and to formulate the idea of comitas and of vested rights (→Vested rights theory).

Irrespective of the very general nature of the statute categories (especially as described by d’Argentré), statutists can be considered as incarnating the first unilateralist period because of the process of reasoning adopted at the time. As Gutzwiller phrased it: ‘for them the problem lies in the rule of decision. Rules (or statutes) are the sole object of consideration. No specific provision regulates conflict of laws, because the solutions are inherent to the text of the statutes’ (Max Gutzwiller, ‘Le développement historique du droit international privé’ (1929) 29 Rec. des Cours 291, 312, the translation is ours).

2. Rise of multilateralism – Europe from the middle of the 19th century

Two important developments took place in the middle of the 19th century, under the influence of which private international law progressively abandoned the statutist school and its unilateral roots. On the one hand, in Italy, Pasquale Stanislao Mancini (→Mancini, Pasquale Stanislaop. 1781) proposed new grounds for private international law, ie the model of the nation state and the corresponding generalization of nationality as a factor for designating the applicable law. On the other hand, Savigny completed his opus on private law with a book dedicated to conflict of laws. Savigny is commonly considered the father of multilateralism, even if he probably restated ideas that were circulating at the time. For Savigny, each legal relationship has a natural seat (Sitz), ie a place where it belongs in regard to its characteristics. Savigny anchors relationships within legal systems, with the help of connecting factors designed for each type of legal relationship. In contrast, the statutists were identifying the spatial scope of statutes by reference to their content and object. Savigny held the two ways of conceptualizing the conflict-of-law issue (‘who is submitted to a specific statute?’ or ‘which law applies to a specific person?’) for equivalent and as leading to identical results (Friedrich Carl von Savigny, System des heutigen römischen Rechts, vol 8 (Veit und Comp 1849) 48, 55). The equivalence between the two methods can be explained by Savigny’s conception of law and legal systems, and the reason why he favoured the second method (now called multilateral) a result of the spirit of the time. Savigny’s system is rooted in the belief that different statutes are merely various expressions of common legal concepts (in Savigny’s vocabulary, ‘Institutionen’) shared by all Christian nations influenced by Roman law. Legal relationships are themselves the visible form of these common concepts and the expression of a legal community rooted in a society shaped by Roman and Catholic heritage (the ‘Volksgeist’). For this reason, statutes are interchangeable and the spatial scope of the one naturally corresponds to the spatial scope of the other. It is therefore possible to identify the ‘seat’ of a legal relationship, because all the relevant statutes will apprehend this relationship in similar terms and identify their own scope in similar ways. Within the limits of this legal community, the (now called) unilateral and multilateral methods are thus equivalent and Savigny favoured the method consisting of identifying the seat of a legal relationship, as a mirror image of the domicile (Sitz in German) of individuals. Indeed his whole conception was also inspired by the liberal spirit of the time and therefore focused on the individual and the expressions of its free will. Since legal relationships are considered a mere extension of individuals, Savigny localizes legal relationships, as he localizes individuals, on the basis of their connection to a legal community, ie their seat (for more details see Pierre Gothot, ‘Simples réflexions à propos de la saga du conflit de lois’ in Marie-Noelle Jobard-Bachellier and Pierre Mayer, Le droit international privé: esprit et méthodes – Mélanges en l’honneur de Paul Lagarde (Dalloz 2005) 343, 349–54).

What remains of Savigny’s legacy is the multilateral method, detached from the reasons why Savigny conceived it in the first place. The idea of a legal community has been long abandoned and intensive migrations have shown that even for individuals, the identification of a seat can be a thorny issue. Nevertheless the multilateral method has proven very useful and received tremendous success in court rooms, as well as in codification. Multilateralism dominates the conflict-of-laws practice and debates in Europe. Interestingly, despite this clear dominance of multilateralism, unilateralism remained part of the debate, be it in order to advocate a unilateralist system or to highlight incoherencies of multilateralism (an almost comprehensive overview until the middle of the 20th century can be found in Rudolf Wiethölter, Einseitige Kollisionsnormen als Grundlage des Internationales Privatrechts (Walter de Gruyter & Co 1956); Wiethölter was unaware of the writings of Quadri). Repeatedly, scholars proposed (sometimes for different reasons) unilateralist systems.

Like the statutists, Pillet attempted to identify the proper scope of statutes by reference to their social function and to organize statutes in two categories: laws that apply to everyone present in the forum, even foreigners, and laws that follow the nationals even when they are abroad. Potential conflicts between laws were to be solved, in his view, via public international law (→Public international law and private international law) imposing a mutual respect for equal sovereigns and favouring the application of the law of the state, having the highest interest in the application of its law. Based on totally different premises, his follower, Niboyet, proposed to implement unilateralism in a controversial project of codification of French private international law that was never adopted (cf Les travaux de la réforme du Code Civil, année 1948–49 (Sirey 1950) 716). Before him, in Germany, authors like Schnell and Niedner believed that private international law had the p. 1782sole function of setting the limits of the substantive law of the forum and not to decide when foreign law should apply (Alexander Niedner, Einführungsgesetz vom 18.8.1896 (Kommentar) (2nd edn, Heyman 1901); Julius Schnell, ‘Über die Zuständigkeit zum Erlaß von gesetzlichen Vorschriften über die räumliche Herrschaft der Rechtsnormen’ [1895] Niemeyers Zeitschrift für internationales Recht 337). In the same period, the German Bundesrat adopted a first codification of private international law, mainly composed of unilateral rules.

Pilenko and Quadri are two interesting examples of modern forms of unilateralism in Europe. For Pilenko (a Russian professor), laws are necessarily composed of three aspects: a substantive aspect, a temporal aspect and a spatial aspect (Aleksandr A Pilenko, ‘Droit spatial et droit international privé’ (1954) 5 Jus Gentium 35–59; ‘Le Droit spatial et le Droit international privé dans le projet du nouveau Code Civil français’ (1953) 6 R.H.D.I. 319–55). Those three elements are interdependent and cannot exist without one another. The question of spatial reach of laws is therefore a matter of domestic law, not of private international law, and is necessarily solved in unilateral terms (by ‘monovalent rules’ forming the ‘droit spatial’, ie the branch of law considering the spatial reach of domestic rules). Pilenko shows with examples that acknowledging the spatial scope of rules actually prevents conflicts (in terms that anticipate those later used by Brainerd Currie (→Currie, Brainerd) about false conflicts). It is only when the internal spatial delineation of two laws of different origin collide that private international law and its ‘polyvalent’ rules come into play, thus late in the reasoning. Pilenko’s system, even though it leaves room for multilateral rules obtained through a process of generalization of the unilateral/monovalent rules, is unilateralist in its premises because it starts with the observation of the spatial reach of internal rules. In contrast, Rolando Quadri’s system is entirely unilateralist (Rolando Quadri, Lezione di diritto internazionale privato (5th edn, Liguori 1969); and the famous article of Pierre Gothot, ‘Le renouveau de la tendance unilatéraliste en droit international privé’ (1971) 60 Rev.crit.DIP. 1, 209, 415, who introduced Quadri’s system in the French literature). It rests on an elaborated conception of laws: as the result of accumulated social experiences, laws regulate specific situations and intend to command individual actions. As such, laws, by nature, determine their own scope of application, including in their spatial aspects. Laws are seen as the direct product of social experience. Therefore applying laws without consideration for the way they describe their own scope of application denatures them and leads to absurd situations where foreign laws are applied to situations they were not intended to cover. Also, as for Pilenko, conflicts occur only when the laws of different countries intend to cover the same situation. Forum law is recognized as having priority when the situation falls within its scope. For the rest, each system recognizes foreign legal systems and coexists with them in an autonomous way, but also searches for coordination and respect for the imperativity of foreign norms which apply according to their own terms through a process of ‘auto-collegamento’, a sort of ‘self-designation’. Quadri’s system, together with Currie’s system, will be explained in more detail infra since it probably incarnates best the contemporary unilateralist thinking (II.).

3. A contrasted picture – the USA as from the 19th century

Almost a contemporary of Quadri, Brainerd Currie launched a vast unilateralist movement in the USA in the 1950s and early 1960s. Currie fought against the formalism of the first Restatement (Restatement (First) of Conflict of Laws, American Law Institute, Restatement of the Law, First: Conflict of Laws, St. Paul 1934). Story had in the 19th century imported the three maxims of Huber (→Huber, Ulrik) and explained on their basis the complicated case-law of common law countries on conflict of laws (Joseph Story, Commentaries on the Conflict of Laws, Foreign and Domestic (Little & Brown 1834)). On the basis of Story’s writing and influenced by Dicey’s (→Dicey, Albert Venn) idea of vested rights, Beale elaborated the first Conflict Restatement. The first Restatement identified through rigid rules (usually resting on territorial connecting factors) the competent state for creating the rights and obligations. In contrast, Currie saw the conflict problem not as a matter of vested rights but as a conflict between laws of different states whose interests might be at stake, or not, depending on the factual situation. The application of a law should only be considered if an ‘interest analysis’ (→Interest and policy analysis in private international law) reveals that this law commands its application to the case at hand in regard of its purpose and of the facts pattern p. 1783(Brainerd Currie, Selected Essays on the Conflict of Laws (Duke University Press 1963)). Currie’s system, inspired by legal realism (and prompted among others by Cook’s seminal article: Walter Wheeler Cook, ‘The Logical and Legal Basis of the Conflict of Laws’ [1924] Yale L.J. 457), is thus based on the premise that states express political, social and economic interest in their statutes and that any conflict-of-laws solution should start with identifying these interests. It also empowers the judge with the role of interpreting the statutes in order to distinguish false conflict (when only one state is interested) from true conflicts (when more than one state is interested).

Currie’s conception of laws echoes Quadri’s even though he was not aware of the Italian scholar’s writings and despite the fact that his methodology was not formulated in view of the unilateralism v multilateralism debate. His idea of state interests and of a need for consideration for the substantive and political content of the rules at stake has been shared by many of his US colleagues, even though each of them proposed alternative solutions, mainly in regard of true conflicts, in order to depart from Currie’s tendency to favour forum law. Baxter’s ‘comparative impairment’ approach, Leflar’s‘better law approach’, Caver’s ‘principle of preference’, Von Mehren and Trautman’s ‘functional analysis’, Weintraub’s ‘consequences based approach’ share the conception of laws bearing a political content having an impact on their spatial scope. Later American scholars thus followed Currie’s intuition in various ways (see Symeon C Symeonides, ‘The American Choice-of-Law Revolution in the Courts: Today or Tomorrow’ (2003) 298 Rec. des Cours 1, 48–58). The Second Conflicts Restatement (Restatement (Second) of Conflict of Laws, American Law Institute, Restatement of the Law, Second: Conflict of Laws 2d, St. Paul 1972) tries to find a balance between the premises highlighted by Currie and the need for rules, in identifying the law with which the situation presents the ‘most significant relationship’ in regard to a series of factors enumerated in its § 6 referring, among others, to the state’s interest.

II. Theoretical background and concepts

As a general theory, unilateralism proposes a system of ideas explaining the problem of private international law and the appropriate solutions thereof. The theory rests on two paradigms deeply rooted in legal theory and leads to consequences regarding the way of solving conflict of laws (II.1., II.2.). Depending on the historical period of time and on the scholars, unilateralism has been considered capable of grounding a system of private international law (II.3.) or simply as the basis for specific tools of private international law, ie for a method illustrated in specific conflict rules (II.2., III.).

1. Unilateralist paradigms

Despite the diversity of its protagonists and of their slightly differing conceptions, unilateralist theory (or rather all unilateralist theories) rests on the idea that laws prescribe their own scope of application for domestic as well as international situations. This idea constitutes the first paradigm of unilateralism. The delineation of the scope of application derives from the substantive content of the rule, from its goal and purposes, and as such can only be addressed by the law itself, either in a specific and express rule or as an inherent and implicit part of the normative (substantial) content.

The second paradigm of unilateralism derives from the first one. It is for each legal order to prescribe for itself when and to what extent its rules should apply to international (as well as domestic) situations. Therefore no legal order can decide that a foreign law applies to a specific relationship if this law does not command its application. Correlatively, it is for each legal system to decide when and how it considers the application of a foreign rule that covers the situation. Obviously, the range of foreign laws to be taken into consideration is limited to those in the scope of which the situation falls. However nothing compels a given legal system to apply those rules, but for an autonomous decision to consider their application.

Unilateralist theory is therefore first and foremost enshrined in a specific conception of the law. Be they of public or private nature, laws are seen as bearing a substantive content aiming to achieve specific goals and therefore covering specific situations. As such, they are not ‘neutral’ (as they can be considered in the multilateralist theory, infra, III.). For instance, in France, Pillet expressed this in his concept of the ‘social function of laws’, and in the USA, Currie, in his ‘interest analysis’.

Beyond a specific conception of rules, unilateralism has been, time and again, depending on doctrinal readings, considered as deriving from p. 1784sovereignty. More recently, unilateralism has been considered the private international law version of pluralism, understood as a general theory of relationships between legal orders (the idea is present though not formulated as such in the famous article of Pierre Gothot, ‘Le renouveau de la tendance unilatéraliste’ (1971) 60 Rev.crit.DIP 1–36, 209–43, 415–50, resting on the conceptions of Quadri and Santi Romano; see later Didier Boden, ‘Le pluralisme juridique en droit international privé’ (2005) 49 A.P.D. 275–316, for a more detailed explanation of the link between pluralism and unilateralism).

2. Unilateralist method

In describing the paradigms of unilateralism and their theoretical roots, much has already been said about the unilateralist method. The essence of the method is to take stock of the ‘will of application’ of the laws in presence. As a result, conflicts of laws exist only if two (or more) laws from different legal systems intend to regulate the situation. In the unilateralist vision based on sovereignty, and nourished by a universalist conception of private international law (ie the belief that common conflict solutions could be found outside of each legal system), the conflict is merely potential: it is avoided through allocation rules deriving from rationality or public international law. For later unilateralists, the concept of conflict of laws is not a potentiality but rather a reality that occurs, in practical terms, in specific situations. For Currie, ‘true conflicts’ arise when more than one state is ‘interested’ in applying its law, as the result of a match between the substantive policies of the state on the one hand and the factual specificities of the case on the other hand. For Quadri, conflicts of laws arise when two substantive laws from different origins cover the same situation.

Leaving aside the statutist period, scholars who proposed a unilateral system commonly agreed on two steps of reasoning. The first step considers the application of forum law. If the situation falls within the spatial reach of forum law, it should be applied. If forum law does not regulate the situation, the second step consists in analysing the application of foreign laws (→Foreign law, application and ascertainment). The task is thus to identify relevant foreign law or laws that intend to regulate the specific situation at hand. Divergences can be traced regarding the way in which the scope of application of forum law is determined and regarding the way in which to deal with conflicts of foreign laws.

On this basis, several characteristics of unilateralism can be identified.

First, the applicability of a law is determined by its own spatial reach, or its ‘own intent of application’. This scope of application is inherent to every law, either expressly or implicitly, and must be derived from the law itself. The same method is therefore used to select the applicable law, be it the lex fori or foreign law: by reference to the predetermined scope of application of this law. The difference between forum and foreign law lies in the natural priority reserved to forum law.

Second, unilateralism aims at applying foreign law without distorting it. The ground for applying foreign law lies indeed in what foreign law states/says about itself, ie whether it requires its own application or not. A common feature of unilateralist tenets is to consider that forum law (including forum conflict rules) cannot determine the hypothesis of application of foreign law. This idea, which is fundamental in contemporary unilateralism, was not so clear in earlier versions of unilateralism based on sovereignty because →ius gentium or higher principles were believed to limit sovereignty (and thus the spatial scope of rules) for every sovereign equally.

Third, unilateralism in its different versions considers that the coordination with foreign legal systems is an integral part of the reasoning process, even when ascertaining the application of forum law. In coordinating with foreign legal systems, the stability of individual situations should be protected. This concern was formulated in various ways over time. Pillet was looking for a principle of ‘common conciliation’ in order to ensure the highest level of respect of sovereignty. Currie developed the ‘moderate and restrained approach’, according to which a state, in ascertaining its interest in applying its own law, should take into account the legitimate interest of other states to have their law applied to the case at hand. For Quadri, a principle of coordination with foreign legal systems guides each national system of private international law with the view of ensuring the stability of individual situations or, in other words, the uniformity of decisions. This principle, however, is not derived from higher norms of conduct (such as →ius gentium or →comity), but constitutes an inherent part of national systems of private international law.

p. 1785Fourth, unilateralism obviously needs to develop alternative solutions for true conflicts, ie the hypothesis where two (or more) foreign laws require their application to the case at hand. This is certainly the trickiest issue for unilateralism. Currie finally proposed that the judge seized with what he called a problem of ‘disinterested third State’ should decline jurisdiction on →forum non conveniens grounds or apply forum law (Brainerd Currie, ‘The Disinterested Third State’ (1963) 28 LCP 754). His followers developed more convincing models, like the comparative impairment approach of Baxter. Pilenko renounced unilateralism at this stage and considered that this is the only question resorting to private international law and to be solved with multilateral rules (which could be obtained through generalizing the unilateral forum rule). The problem is equally insurmountable for unilateralism based on sovereignty: any solution amounts to bowing to one sovereign’s affirmation of power over another sovereign’s affirmation of power. But tenets of this school partially denied the possibility of such conflicts, since the allocation of sovereignty (coming from jus gentium or some other superior rationale) was deemed to prevent them. When unilateralism is rooted in the conception of the law, as for Quadri, concurring claims of different states for applying their own laws are less problematic. For Quadri, if the system rests on the respect of what each state decides for itself, it is also based on a pragmatic evaluation of the facts in order to ensure the stability of the individual situation. Therefore, a search for effectiveness favours the application of the law that in practice has the best chance of applying and that corresponds (as a consequence) to the expectation of the parties (Rolando Quadri, Lezione di diritto internazionale privato (5th edn, Liguori 1969) 221).

Fifth, unilateralism encounters another difficulty, called lacuna or, in Currie’s vocabulary, the ‘unprovided for’ case, ie situations where no law claims its application. Applying the lex fori solves this problem. Niboyet grounded this solution in the territoriality principle. Currie justified this solution as a matter of convenience for the judge and of common sense, because no other option can really be considered as a more favourable alternative. In order to promote the stability of individual situations, Quadri added (to the option of applying forum law) the option of applying the law which the parties thought applicable and according to which they had behaved.

3. Unilateralist system

A unilateralist system is a system of private international law entirely derived from the unilateralist paradigm and resting exclusively on the unilateralist method. Such a system has been proposed repeatedly throughout history but has barely materialized, with the notable exception of the statutist period. The true point of divergence between a unilateralist and a multilateralist system concerns the designation of foreign law: for unilateralism, forum law cannot determine the hypothesis of application of foreign law (→Foreign law, application and ascertainment), this can only be done by foreign law. The reluctance of private international law systems to select foreign applicable law on the sole ground of its ‘intention’ to apply is the reason why a comprehensive unilateralist system is lacking.

In Europe, attempts to create a unilateral system have taken the form of unilateral rules on the application of forum law. But concerning the application of foreign law, national judges have developed an analogy reasoning, called ‘multilateralization’, using the applicability criteria of forum law as a factor for designating the foreign law applicable irrespective of what the latter indicates about its own applicability. For instance, the early codification of private international law in →Germany was at first conceived on a unilateralist mode, but when confronted with the need for solving cases where German law was not applicable, German judges had recourse to the analogy reasoning. The same phenomenon occurred in →France and →Belgium where the few provisions of the Civil Code (the ‘Code Napoléon’) dedicated to international situations were formulated in a unilateral way, but were later submitted to an analogy reasoning allowing for the application of foreign law (for France and Germany: Gérard Vivier, ‘Le caractère bilatéral des règles de conflit’ [1953] Rev.crit.DIP 655, 656–8 [1954] 73, 86–7). The natural tendency towards ‘multilateralization’ of unilateral rules has been explained by the need for judges to find a legal basis for applying foreign rules in positivist systems (Marc Fallon, ‘L’application de l’article 3, alinéa 3, du Code civil par la jurisprudence belge du 19e siècle’ in Colloque p. 1786François Laurent, Gand, 4–8 September 1987 (Story 1989) 765).

In the USA, only two states still practise the approach advocated by Currie (California and District of Columbia, where interest analysis is used for torts: Symeon C Symeonides, ‘Choice of Law in the American Courts in 2013: Twenty-seventh Annual Survey’ (2014) 62 Am.J.Comp.L. 2). However, as Symeonides has shown, most of the current approaches in the USA are, at least partially, based on unilateralism in the sense that ‘the purposes, policies, or interests underlying the laws from which the selection is to be made’ are taken into consideration (Symeon C Symeonides, ‘The American Choice-of-Law Revolution in the Courts: Today or Tomorrow’ (2003) 298 Rec. des Cours 1, 365, 375). In particular, § 6 of the Restatement (Second) of Conflict of Laws places the relevant policies of the forum and other interested states among the factors guiding the selection of the applicable law. In practice, courts tend to emphasize the factors of § 6 dealing with states’ interests, so that Currie’s influence on the current practice of conflict of laws in the USA remains remarkable.

Interestingly, despite the absence of a comprehensive unilateralist system, unilateralism has remained vivid in various ways. First, unilateralism remains, even recently, a strong source of inspiration for doctrinal writings, be it for proposing a new system, for explaining new techniques or new phenomena. Second, legislators (both in the EU and in the USA) have enacted statutes that are obvious examples of the unilateralist method. As Gothot and Wiethölter underlined, unilateralism also offers an opportunity for challenging and re-conceptualizing the dominant multilateral theory (Pierre Gothot, ‘Le renouveau de la tendance unilatéraliste’ (1971) 60 Rev.crit.DIP 1, 6; Rudolf Wiethölter, Einseitige Kollisionsnormen als Grundlage des Internationalen Privatrechts (Walter de Gruyter & Co 1956) 122), which will now be compared.

4. Unilateralism v multilateralism

Points of divergence between unilateralism and multilateralism have been mentioned above but need to be summarized as a conclusion on the theoretical background.

The fundamental difference between multilateralism and unilateralism is the conception of the rule of law. After the idea of a legal community, which grounded Savigny’s conception (supra), had been abandoned, multilateralism has received alternative foundations. The most convincing ground for multilateralism lies in a concept of rules of law as being the incarnation of rationality, thus a neutral, non-political object and virtually universal. Laws are thus unable to determine their own spatial scope of application for the reason that as purely rational objects, they can encompass any situation corresponding to their hypothesis, irrespective of the geographical and personal features of the situation. The unlimited character of laws explains why it is possible to apply foreign laws and why forum law can apply to facts localized outside the forum (Pierre Mayer, ‘Le phénomène de la coordination des ordres juridiques étatiques en droit privé’ (2007) 327 Rec. des Cours 1, 140–51). To put it in short, law is more a model for action of individuals, than a practical command of their action (Pierre Mayer, ‘Le phénomène de la coordination des ordres juridiques étatiques en droit privé’ (2007) 327 Rec. des Cours 1, 149). As shown above, the unilateralist concept of laws differs profoundly from this vision, also because unilateralists probably have a more pragmatic rather than abstract approach to law.

As a result of the diverging concept of laws, unilateralism and multilateralism have opposing views on conflict of laws: in a multilateral system, national laws, because they do not limit their scope, are considered as virtually always in a state of conflict, whereas in a unilateralist system, conflicts occur only when two laws are proved to effectively cover the same factual situation. The first role of the judge in a unilateralist system is thus to identify the conflict.

Finally, the methods for solving conflicts differ in nature. The preceding section (supra II.2.) shows that the unilateralist method is closer to an ‘approach’ than a set of rules: the system rests upon an observation of laws in conflict with adaptation mechanisms for true conflict and lacuna. In contrast, multilateralism must give rise to a set of rules because the judge needs to refer to a rule delimiting the scope of application of the laws virtually in conflict. Such conflict rules are thus necessary in every field of law.

III. Practical contemporary implications

Even if unilateralism is a marginal theory in contemporary private international law, most systems of private international law use some p. 1787unilateral tools. As many of these tools or methods are discussed in other entries of the Encyclopedia, we will only mention here how and why they echo unilateralism. These various examples illustrate how lawmakers regularly feel the need to identify the international scope of their norms.

1. Unilateral conflict rules

Unilateral conflict rules are conflict rules having the sole function of designating the lex fori (or more generally the law of the state having enacted them). Truly unilateral conflict rules are formulated in terms that render their multilateralization impossible and are therefore rather rare. Indeed most conflict rules initially formulated in unilateral terms (such as the provisions of the first Introductory Act to the German Civil Code (Einführungsgesetz zum Bürgerlichen Gesetzbuche of 21 September 1994, BGBl. I 2494, as amended) or art 3 of the French Civil Code (Code Civil of 21 March 1804; henceforth French CC) were easily submitted to a multilateralization process. In contrast, rules like the former art 330 of the French CC cannot lead to the designation of foreign law through analogy reasoning. Now replaced by the →Rome III Regulation (Regulation (EC) No 864/2007 of the European Parliament and of the Council of 11 July 2007 on the law applicable to non-contractual obligations (Rome II), [2007] OJ L 199/40), art 330 of the French CC states that divorce and legal separation are submitted to French law:

  • when both spouses are French nationals

  • when both spouses have their domicile on the French territory

  • when no other law finds itself competent and French courts have jurisdiction over the divorce or legal separation.

To a certain extent, these unilateral conflict rules are comparable to the overriding mandatory rules mechanism. Indeed a unilateral conflict rule delineates the scope of forum law and ensures its application to the situations covered. Unilateral conflict rules however determine the hypothesis of application not only of a specific statute (like overriding mandatory rules), but of an unlimited amount of provisions (like the rules on divorce or legal separation (→Divorce and personal separation)). Also, in contrast to international mandatory rules, the provisions designated by the unilateral conflict rules are not necessarily imperative.

Unilateral conflict rules are thus an expression of unilateralism in the sense that they determine the scope of application of forum law, without deciding on the hypothesis of application of foreign law (→Foreign law, application and ascertainment).

2. Rules of applicability, self-limited rules, substantive rules of private international law

Rules of applicability are rules which determine the scope of a specific set of provisions, like a domestic statute, an international agreement or a piece of European secondary law (on this notion: Marc Fallon, ‘Les règles d’applicabilité en droit international privé’ in Mélanges offerts à Raymond Vander Elst, vol 1 (Nemesis 1986) 285). The various aspects of the scope of application (time, space, substance) are usually spread in various provisions. The most relevant of them, for private international law purposes, is the rule concerning the spatial scope, ie identifying the situations covered by the set of provisions with regard to their connections with one or more contracting states (for international conventions) or the state or legal system to which the rule belongs (for domestic statute and EU rules). Rules of applicability are necessarily unilateral: they state when a specific statute of state A applies to an international situation. This role is very close to the one of unilateral conflict rules with the only difference that rules of applicability refer to a specific (and not unlimited) set of provisions. They may determine the scope of mandatory provisions (as in overriding mandatory rules, infra III.3.), as well as non-mandatory provisions.

Examples of applicability of rules are as diverse as art 2 of the Athens Regulation (Regulation (EC) No 392/2009 of the European Parliament and of the Council of 23 April 2009 on the liability of carriers of passengers by sea in the event of accidents, [2009] OJ L 131/24) (stating that the regulation applies to international carriage ‘where the ship is flying the →flag of or is registered in a Member State or, the contract of carriage has been made in a Member State or the place of departure or destination . . . is in a Member State’), art 1 (1) a) of the →CISG (United Nations Convention of 11 April 1980 on Contracts for the International Sale of Goods, 1489 UNTS 3) (stating that the Convention applies to international sales p. 1788contracts when the two parties are established in contracting states) or art L-3122-1 of the French public health code (Ordonnance 2000–548 of 15 June 2000 on the legislative part of the Code of Public Health, JORF No 143, 22 June 2000, p 9340) (limiting the scope of the fund established for victims having been infected by HIV after a blood transfusion to cases were the transfusion occurred on the territory of the French Republic; see Cass Civ II France, 3 February 2005 (2005 II) 24 Bulletin 22).

The doctrine (with some diversity in the vocabulary) usually distinguishes between rules of applicability influencing the conflict-of-laws solutions and rules of applicability that are relevant only after the law of the state they belong to has been selected as the applicable law. Self-limited rule and substantive rules of private international law belong to the second category. A self-limited rule restricts the reach of a specific statute to some determined domestic situations (for instance, a specific statute that would apply only in part of the territory of a state). It thus operates a distinction between a special statute and other more general statutes or, in some countries, the common law. Substantive rules of private international law are those domestic rules whose content makes sense only for international situations, without identifying precisely those situations and thus without impacting the conflict-of-law reasoning. For instance, in →Belgium, a provision on employee protection states that when the employee works abroad, he may choose to be paid in the currency valid in Belgium or in the state where he works (art 4 of the Law of 12 April 1965 on the protection of remuneration (Loi du 12 avril 1965 sur la protection de la rémunération des travailleurs, MB, 30 April 1965, 4710)).

Of course, despite the nuances, these various provisions express the need felt by the legislature to identify the scope of its provisions, in regard of international or domestic situations. When they relate to identified international situations, rules of applicability obviously have an influence on the conflict-of-law process. As special rules, they derogate to the general multilateral choice-of-law rules.

3. Overriding mandatory rules

Overriding mandatory rules are the most widespread example of using unilateralism as a tool in private international law and probably the best accepted in contemporary legislation on private international law (lois de police/Eingriffsnormen). Indeed, specific provisions on international mandatory rules can be found in EU Regulations (art 9 Rome I Regulation (Regulation (EC) No 593/2008 of the European Parliament and of the Council of 17 June 2008 on the law applicable to contractual obligations (Rome I), [2008] OJ L 177/6; →Rome Convention and Rome I Regulation), art 16 →Rome II Regulation (Regulation (EC) No 864/2007 of the European Parliament and of the Council of 11 July 2007 on the law applicable to non-contractual obligations (Rome II), [2007] OJ L 199/40)), in national codifications (for instance, art 10:7 of the Dutch New Civil Code (Boek 10 Burgerlijk Wetboek, Wet van 19 mei 2011 tot vaststelling en invoering van Boek 10 (Internationaal privaatrecht) van het Burgerlijk Wetboek (Vaststellings- en Invoeringswet Boek 10 Burgerlijk Wetboek), Staatsblad 2011, 272), art 19 Swiss Private International Law Act (Bundesgesetz über das Internationale Privatrecht of 18 December 1987, 1988 BBl I 5), art 20 of the Belgian Private International Law Act (Wet houdende het Wetboek von international privaatrecht/Code de droit international privé of 16 July 2004, BS 27 July 2004, pp 57344, 57366), art 4 Statute of Application of Law to Foreign Civil Relations (adopted at the 17th session of the Standing Committee of the 11th National People’s Congress on 28 October 2010, effective 1 April 2011)), as well as in international conventions (for instance, art 11 of the Inter-American Contracts Convention (Inter-American Convention of 17 March 1994 on the Law Applicable to International Contracts, 33 ILM 732); art 16 of the Hague Agency Convention (Hague Convention of 14 March 1978 on the law applicable to agency, Hague Conference of Private International Law (ed), Collection of Conventions (1951–2009) (Intersentia 2009) 268); art 17 of the Hague Convention of 22 December 1986 on the law applicable to contracts for the international sale of goods ((1985) 24 ILM 1575); art 11 of the Hague Securities Convention (Hague Convention of 5 July 2006 on the law applicable to certain rights in respect of securities held with an intermediary, 46 ILM 649)) and model laws (for instance, art 11 of the Hague Principles on Choice of Law in International Commercial Contracts (approved on 19 March 2015, available at <www.hcch.net>); art 1.4. of the UNIDROIT Principles (International Institute for the Unification of Private Law/p. 1789Institut international pour l’unification du droit privé, UNIDROIT Principles of International Commercial Contracts 2010 (3rd edn, UNIDROIT 2010))). These provisions systematically allow the application of international mandatory rules of the forum, but not always those of other interested states.

Overriding mandatory rules are a topical example of unilateralism. As identified in the definition proposed by Francescakis (Phocion Francescakis, ‘Conflits de lois (principes généraux)’ in Dalloz, Encyclopédie juridique, Repertoire de droit international, vol 1 (Dalloz 1968) no 137) and later by the ECJ (Joined Cases C-369/96 and C-376/96 Criminal proceedings against Jean-Claude Arblade and Arblade & Fils SARL and Bernard Leloup, Serge Leloup and Sofrage SARL [1999] ECR I-8453) and by the European lawmakers in art 9(1) of the Rome I Regulation, they are characterized by three components. First, they fix their own scope of application through an implicit or explicit applicability rule. Second, their scope of application reflects their specific purpose, aiming at the protection of essential interests of the state. Third, this purpose justifies their need to derogate from the general conflict rules.

Overriding mandatory rules are thus the most direct expression of the link between the aim of a statute and its scope regarding international matters. The mandatory aspect of those rules (displacing party autonomy and the designation operated by objective conflict rules) might have led to some confusion, in the sense that doctrine tends to assimilate any statute stating its scope of application with an overriding mandatory rule. However, the expression of the scope of applicability of a statute and its degree of imperativity are different matters (Stéphanie Francq, L’applicabilité du droit communautaire dérivé au regard des méthodes du droit international privé (Bruylant/LGDJ 2005) 421–41, 575–6, 643).

The most perfect example of unilateralism (and the most controversial) occurs when a system of law is ready to apply international mandatory rules belonging to a system of law that has not been designated by the multilateral conflict rule. In this case, there are only two identifiable bases for applying a foreign mandatory rule. First, the latter requests its application to the case at hand. In other words, foreign law applies according to its own terms. Second, the forum wishes to harmonize with the foreign legal system, thus furthering the other system’s policies.

4. Renvoi

Though it is not a direct product of unilateralism, the technique of renvoi expresses the concern of unilateralism towards the opinion of foreign systems on the application of their own rules. In other words, renvoi is based not only on the idea of uniformity of result, but also on an attempt to prevent the ‘forced’ application of foreign substantive norms when the system they belong to does not consider them applicable to a specific situation.

5. EU regulations and directives

Within the European Union, EU regulations and directives (ie secondary Union law) offer another illustration of unilateralism in the sense that they determine their own scope of application, through implicit or explicit rules of applicability. Examples of recent explicit rules of applicability are found in regulations as well as directives (for a regulation, see among others: art 1 of Regulation (EU) No 236/2012 of the European Parliament and of the Council of 14 March 2012 on short selling and certain aspects of credit default swaps ([2012] OJ L 86/1); art 1, 3 of Directive 2014/17 on credit agreement for consumers relating to residential immovable property (Directive 2014/17 of the European Parliament and of the Council of 4 February 2014 on credit agreements for consumers relating to residential immovable property and amending Directives 2008/48/EC and 2013/36/EU and Regulation 1093/2010, [2014] OJ L 60/34)). Even in the absence of an explicit rule, the scope of application of EU secondary legislation derives from its purpose and can be identified through a literal or teleological interpretation process (Stéphanie Francq, L’applicabilité du droit communautaire dérivé au regard des méthodes du droit international privé (Bruylant/LGDJ 2005)). The reasons for this extensive use of the unilateral method in European law are debatable. On the one hand, regarding the wide margin of appreciation of the EU lawmaker, the principle of limited power cannot offer a final explanation. On the other hand, since party autonomy is not systematically excluded, EU legislation determining its own scope of application cannot be entirely assimilated to overriding mandatory norms. In the end, EU regulations and directives illustrate the spontaneous use of the unilateral method by a lawmaker thinking in functional terms. p. 1790Preoccupied with achieving a specific social or economic goal, the EU lawmaker tends to provide indications on the international scope of its statute. The ECJ has shown how the scope of the agency directive, for instance, directly resulted from its purpose in the famous and controversial Ingmar case (Case C-381/98 Ingmar GB Ltd v Eaton Leonard Technologies Inc [2000] ECR I-9325, Opinion of G Léger I-9307) and established the link between the purpose and substantive content of a directive on the one hand and the interpretation of the provisions of its scope of application in the Google case on the other (Case C-131/12 Google Spain SL and Google Inc v Agencia Española de Protección de Datos (AEPD) and Mario Costeja González (13 May 2014) § 52, 53, 57). Since the reasons why the EU lawmaker uses unilateralism are valid for any law, the author considers that unilateralism should receive wider acceptance.

IV. Theoretical contemporary significance

As mentioned earlier, unilateralism continually questions the dominant multilateral system. The concerns carried out by unilateralism regarding the link between the scope and the aims of a statute, respect for foreign legislature’s conceptions about the scope of their own laws, and consistency of private situations are echoed in contemporary discussions on the theory and methods of private international law (→private international law, methods of). Again, the following lines simply highlight how traces of unilateralism can be found in modern theoretical debates, rather than providing for a full account of those debates.

1. International economic law / Wirtschaftskollisionsrecht

In the field of international economic law, unilateralism is dominant (Jürgen Basedow, ‘Wirtschaftskollisionsrecht – Theoretischer Versuch über die ordnungspolitischen Normen des Forumstaates’ (1988) 52 RabelsZ 8). As the states became increasingly concerned with the potential negative impact of pure liberalism on individuals and on their own economic market, they developed regulatory intervention motivated by a political (often protective) purpose. Doing so, they naturally used the unilateralist method to assert the application of these regulations concerning for instance, competition, transport or employment. The theory of international economic law is close to the French theory of the ‘lois de police’ (overriding mandatory rules), since all the statutes which are considered as belonging to international economic law could be qualified as ‘lois de police’. But the theory of international economic law tends to allocate a field of law to unilateralism, in contrast to the theory of ‘lois de police’ where the overriding mandatory norms are identified on a case-by-case basis.

2. Conflict-of-systems theory

At the intersection of multilateralism and unilateralism, the conflict-of-systems theory tends to identify a system of law under the auspices of which the situation should be treated. Therefore the designation covers not only the substantive law, but also the rules of conflict of jurisdiction (or authorities) and conflict of laws (Paolo Picone, ‘La méthode de coordination entre ordres juridiques en droit international privé’ (1999) 276 Rec. des Cours 229). Even if the designation operates on a multilateral basis, its object is the foreign system as a whole in consideration of the foreign approach to the appropriate treatment of the situation in private international law terms. Foreign law should not apply unless it is required to do so. Presenting similarities with renvoi, but with an extension to conflict of jurisdiction, the theory integrates part of the unilateral concern with respecting foreign systems, but also the stability of individual situations. In this respect, the theory tends to favour the recognition of situations formed by a competent authority (in regard to its own system).

3. The method of recognition

Under the influence of several important decisions of the ECJ and the ECHR (for instance: Case C-148/02 Carlos Garcia Avello v État belge [2003] ECR I-11613; Case C-353/06 Stefan Grunkin and Dorothee Regina Paul [2008] ECR I-7639; Wagner and JMWL v Luxembourg App No 76240/01 (ECHR, 28 June 2007); Negrepontis-Giannisis v Greece App No 56759/08 (ECHR, 3 May 2011)), it has been proposed to treat private situations that have been ‘crystallized’ (after the term of Pierre Mayer: Pierre Mayer, ‘Les méthodes de la reconnaissance en droit international privé’ in Marie-Noelle Jobard-Bachellier and p. 1791Pierre Mayer, Le droit international privé: esprit et méthodes – Mélanges en l’honneur de Paul Lagarde (Dalloz 2005) 547, 562) in a foreign legal system in the same way as judgments rather than testing their validity under the law designated by the conflict-of-law rules of the forum. Such ‘foreign’ situations would, accordingly, be automatically recognized in the forum unless they contravene specific non-recognition grounds (that would need to be identified). The so-called method of recognition (Paul Lagarde, La reconnaissance des situations en droit international privé: actes du colloque international de la Haye du 18 janvier 2013 (Pédone 2013)) presents similarities with the doctrine of vested rights even though the respect of vested rights was thought of as the object of a multilateral conflict rule. Like the conflict-of-systems theory, it echoes unilateralism in its search for the respect of stability of individual situations and in the trust placed in the foreign system. It is for the foreign system to solve the question of the applicable law and once it has done so, the forum in its recognition process will not revise this choice, nor project its own identification of the applicable law on a situation already existing and established in the foreign system.

4. The natural role of unilateralism

In contemporary doctrine, several authors argue for a more coherent integration of the unilateralist doctrine. These approaches consider it necessary to leave some room (the extent of which depends on the author) to unilateralism, in the theoretical conception of private international law and/or at the more practical level of conceiving conflict rules (in addition to Francq, see: Didier Boden, ‘Le pluralisme juridique en droit international privé’ (2005) 49 A.P.D. 275–316; Andreas Bucher, ‘La dimension sociale du droit international privé’ (2009) 341 Rec. des Cours 9–526; Andreas Bucher ‘Vers l’adoption de la méthode des intérêts ? Réflexions à la lumière des codifications récentes’, Travaux du Comité français de droit international privé 1994–1995 (Pedone 1996) 209–37; Louis d’Avout, Sur les solutions du conflit de lois en droit des biens (Economica 2006); Gian Paolo Romano, L’unilateralismo nel diritto internazionale privato moderno (Schulthess 2014); Symeon C Symeonides, ‘Accommodative Unilateralism as a Starting Premise in Choice of Law’ in Hans-Eric Rasmussen-Bonne, Richard Freer, Wolfgang Lüke and Wolfgang Weitnauer (eds), Balancing of Interests: Liber Amicorum Peter Hay zum 70. Geburtstag (Verlag Recht und Wirtschaft 2005) 417).


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  • Phocion Francescakis, ‘Quelques précisions sur les lois d’application immédiate et leur rapports avec les règles de conflit de lois’ [1966] Rev.crit.DIP 1;

  • Stéphanie Francq, L’applicabilité du droit communautaire dérivé au regard des méthodes du droit international privé (Bruylant/LGDJ 2005);

  • Pierre Gothot, ‘Le renouveau de la tendance unilatéraliste’ (1971) 60 Rev.crit.DIP 1, 209, 415;

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  • Rudolf Wiethölter, Einseitige Kollisionsnormen als Grundlage des Internationalen Privatrechts (Walter de Gruyter & Co 1956).