Philippine Blajan, who is a professor at the University of Versailles Saint Quentin, has published La combinaison des autonomies en droit international privé des contrats. Étude des interactions entre le choix de juridiction et le choix de loi (The Combination of Party Autonomies in the Private International Law of Contracts. A study of the interactions between Choice of Jurisdiction and Choice of Law) with the Éditions de l’Institut de Recherche Juridique de la Sorbonne. The book is based on the doctoral thesis of the author, who received the prize of the Comité français de droit international privé in 2022. The author has provided the following extended summary of her work.
In civil law systems, private international law traditionally approaches the autonomy of parties to international contracts through a familiar summa divisio: on one side, the choice of law; on the other, the choice of jurisdiction (state or arbitral). This conceptual divide structures both the teaching of the subject and its technical rules, especially in European instruments such as Rome I and Brussels I bis, which regulate these freedoms separately.
Yet it fails to reflect an increasingly obvious reality: parties to a contract rarely think in such abstract channels and rigid compartments. Instead, they either strategically combine these tools along with their substantive freedom to shape contractual rights and obligations and to pursue coherent regulatory objectives (the delicate matter of the choice of arbitration and its seat is an eloquent illustration), or unfortunately fail to do so, for lack of awareness of their interactions and potential.
Therefore, the ambition of the book is to offer a conceptual renewal of party autonomy by building a bridge between conflict of laws, conflict of jurisdictions (including arbitration), and substantive contract law. It brings together choice of law (autonomie conflictuelle à objet législatif), choice of forum (autonomie conflictuelle à objet juridictionnel), and contractual freedom (liberté contractuelle or autonomie substantielle), integrates these freedoms in a triangular architecture, and shows that party autonomy is inherently combinatory. Other than theoretical, its practical aim is to better understand the notion, regime and scope of party autonomy in international contracts. The book therefore challenges the traditional dichotomy and proposes a general theory of party autonomy in private international law of contracts based on a combinatory model that accounts for these interactions, shows their “pros and cons” from the parties’ perspective, and provides criteria for regulating them.
I.- Reassessing the Limits of the Dichotomy
The first part of the thesis diagnoses the shortcomings of the classical dichotomy between jurisdiction and choice of law, as well as between autonomy in PIL matters and substantive freedom. It shows that this division, though useful pedagogically, does not correspond to the complex normative reality of international contracting. Two blind spots are identified in this apparently neat separation: internormativity between arbitral and state legal orders and the interdependence between conflictual and substantive autonomies.
A) Internormativity between Arbitral and State Legal Orders
Arbitration is often portrayed as a space of expansive party autonomy; even as a laboratory for “contract without law” (contrat sans loi). Yet such representation oversimplifies the profound and constant circulation of norms between arbitral and state orders. The arbitral order remains significantly permeable to state normativity: parties frequently designate state law to govern their dispute; arbitrators routinely rely on conflict-of-laws methods; and mandatory rules or international public policy may override the chosen law. Even when parties rely on non-state norms such as the lex mercatoria, the reasoning of arbitrators is permeated by state-derived principles.
Conversely, state courts exhibit a form of openness towards non-state or composite normative arrangements. They enforce incorporation clauses (including stabilisation clauses), dépeçage, and other contractual techniques that allow parties to craft highly customised regimes. The risk of turning a blind eye to the interactions between choices of law and jurisdiction is to unintentionally grant parties substantive autonomy of an integral nature, i.e. an almost complete liberation from state law, which would lead to contrats sans loi and to disorder. Contrary to intuition, such risk arises more acutely before state courts than in arbitration, where the normative structure, paradoxically, proves less permeable to strategies aiming at evading state law.
B) Interdependence between Conflictual and Substantive Autonomies
The thesis also shows that choice of forum is never merely procedural. The designated court carries many conflictual and substantive consequences. Selecting a court determines the choice-of-law rule (party autonomy or not) and therefore the applicability (or not) of the chosen law (state or non-state law) and its substantive provisions. Moreover, it determines the relevance and reach of mandatory rules (of the lex fori, the lex contractus and foreign laws with proximity to the contract). Therefore, the choice of court indirectly, yet very significantly, shapes the contract’s substantive regime. This justifies, in the author’s opinion, a strengthened regime for violations of forum-selection clauses, when such violations are motivated by an intent to circumvent the binding force and equilibrium of the main contract, e.g. forum shopping designed to trigger a more favourable law and to avoid mandatory obligations (contractual or legal), or procedural delays. Sanctions may include anti-suit injunctions, damages, and swift declination of jurisdiction by non-chosen courts.
This dynamic also leads to a new analysis of the “neutral judge”: a forum chosen not for geographical or legal proximity but precisely for its lack of it. It appears that this choice can be explained by practical or political reasons, but also by substantial ones: much like arbitration, its appeal lies in the flexibility it offers for constructing a tailored substantive regime. Indeed, judicial “neutrality” entails lack of “interest” of the state in regulating the contracts, and therefore affords parties more freedom to construct a bespoke substantive regime, clear of the interference of the forum’s international mandatory provisions.
Symmetrically, the choice of law influences the effectiveness of forum agreements: some courts consider that the lex contractus governs the substantive validity of jurisdiction clauses; when some others (notably English courts) are sensitive to the proximity between forum and law selected (e. g., choice of English law enhances the likeliness of English jurisdiction, the local courts considering that they are the proper forum or forum conveniens for applying their own law).
Briefly presented, these observations reveal that the dichotomy between law and forum can be misleading: it occults their interactions and that parties may use their combination to shape, optimise, or constrain their substantive autonomy. The dichotomy obscures this reality; the combinatory model clarifies it.
II.- Towards a Combinatory Model of Party Autonomy
Building on this diagnosis, in the second part, the thesis develops the theory of combination of choice of law and choice of court as a distinct legal category. A combination is defined as the conscious articulation of a choice of law and a choice of jurisdiction that jointly configure the conflictual regime of the contract and determine the scope of the parties’ substantive freedom.
Acknowledged as a category containing two families – homogenous and heterogenous, the combination can benefit from an adjusted legal framework.
A) Homogeneous and Heterogeneous Combinations
The thesis constructs a typology of combinations, distinguishing two forms.
On one hand, homogeneous combinations are characterized by law and forum designated within the same normative order (e.g., French court + French law; English court + English law; arbitral tribunal + lex mercatoria). Such combinations enhance coherence and predictability, approximating an internal contract even where international. They offer optimal legal stability while maintaining necessary distinctions between domestic and international settings.
On the other hand, in heterogeneous combinations, law and forum originate from distinct normative orders (e.g., English court + Swiss law; arbitral tribunal + state law; asymmetric jurisdiction clauses combined with dépeçage). These combinations embrace internationality, the contractual engineering it offers, and generate flexible, custom made (but possibly overly complex or unenforceable) composite regimes. Here, the contract becomes even more “internationalised” through its multi-sourced normativity.
Both types of combinations are legitimate, but raise different regulatory concerns, especially when they risk producing (quasi)integral substantive autonomy.
B) A Conflictual Public Order Framework for Regulating Combinations
The thesis then proposes criteria for regulating combinations, through a concept or “conflictual public order” (ordre public conflictuel) focusing on instances where contractual autonomy must be curtailed to protect overriding mandatory rules, the coherence of the international legal order, loyalty in international proceedings and the integrity of private international rules, which offer legitimate freedom, indispensable predictability, but certainly do not aim at, nor serve the purpose of, enabling parties to evade every legal framework altogether.
In direct proceedings, especially before the French courts, the thesis advocates several measures. Firstly, targeted exceptions to the Monster Cable doctrine (Cass. civ. 1re, 22 octobre 2008, n°07-15.823 : « la clause attributive de juridiction contenue dans ce contrat visait tout litige né du contrat, et devait en conséquence, être mise en oeuvre, des dispositions impératives constitutives de lois de police fussent-elles applicables au fond du litige », i.e., a forum selection clause in favour of foreign courts must be applied even where an overriding mandatory rule of the forum seized is applicable to the dispute), allowing French courts to set aside a foreign forum clause when not only its effect, but its main purpose, is to neutralise a French overriding mandatory rule with legitimate international reach, or when the clause (especially if asymmetrical) creates a significant imbalance (déséquilibre significatif) between the rights and obligations of the parties.
Secondly, protection of foreign overriding mandatory rules, where their claim to application is legitimate. Here, the thesis argues for setting aside choice-of-law clauses that defeat such rules.
Thirdly, clearer legal limits on dépeçage, which can resemble functional attempts to escape state law altogether.
Fourthly, and more generally, recourse to the notion of “conflictual public order/policy” (ordre public conflictuel), used to police abusive combinations and maintain the boundary between conflictual autonomy and integral substantive autonomy.
In indirect proceedings (exequatur), the thesis argues for a more robust control of foreign judgments rendered in violation of a forum or an arbitration clause. The same enhanced control is advocated for foreign judgments and arbitral awards rendered in disregard of overriding mandatory rules (whether French or foreign), and a renewed role for the doctrines of fraud, abuse of right, and international public policy, here again understood in a “conflictual” sense, i.e. to prevent misuse of party autonomy as afforded by private international law rules.
Conclusion: A Renewed Theory for a Renewed Practice
The book aims to provide both a strong theoretical and a useful practical contribution to private international law of contract. Theoretically, it reframes party autonomy as a plural phenomenon structured around three distinct yet interrelated freedoms: choice of substantive rights and obligations, choice of law, choice of forum. Practically, it offers a regulatory model, anchored in traditional conflict-of-laws tools, but adapted to contemporary challenges, that could equip courts to address contemporary challenges such as strategic combinations of law and forum, the evasion of legitimate mandatory rules, and the pursuit of quasi-total contractual self-regulation.
Because the will of the parties transcends the methodological grids of conflicts law, courts and legislators should acknowledge this phenomenon and respond by regulating this combinatory logic more effectively. Even though the road ahead seems long considering recent case law (e.g. CJEU, 7 Sept. 2023, C-590/21; Cass. civ. 1re, 15 June 2022, n° 20-23.115; Cass. Civ. 1re, 2 April 2025, n°23-12.384), one can hope that in time, this renewed presentation of party autonomy in private international law of contract might inspire new and better-suited solutions, preserving – in the manner of a tightrope walker – both party autonomy, legal authority and the integrity of the private international law rules of contracts.

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