Books Developments in PIL Scholarship

The Methodology of Overriding Mandatory Provisions in Modern Conflicts of Laws

The public policy exception is used as a shield to protect fundamental domestic values in case of a contradiction between the applicable foreign law and fundamental principles of justice of the forum. Alongside the public policy exception, the instrument of “overriding mandatory provisions” – or “public policy rules” – was established in the middle of the 20th century and is today codified in many acts of European Private International Law (see e.g. Article 9 of the Rome I Regulation). Overriding mandatory provisions are rules of outstanding importance for public order, which the legislator intends to be respected even where a case is governed by foreign law under ordinary conflict-of-laws rules.

The Book

In his PhD thesis Die Methodik der ‘Eingriffsnorm im modernen Kollisionsrecht, published in German and recently honoured with the prestigious Gerhard Kegel Prize, Adrian Hemler describes the problem of applying of overriding mandatory provisions as a symptom of numerous fundamental uncertainties in the doctrines of PIL. In his view, the theory of overriding mandatory provisions obscures the fact that PIL needs further differentiation through conflicts-of-laws rules yet to be developed. Based on this, he sees the function of the public policy exception as a safeguard of the supremacy of constitutional law. In sum, he traces overriding mandatory provisions back to the well-known principle lex specialis derogat legi generali, while also basing the public policy exception on the principle lex superior derogat legi inferiori.

Flash Back

The thesis opens with an in-depth historical analysis. Hemler points out that the distinction between the “positive” enforcement of individual rules through overriding mandatory rules on the one hand and the “negative” protection of fundamental principles through the public policy exception on the other hand has not been made until the second half of the 20th century. In addition, he shows how overriding mandatory provisions have been gradually isolated as rules that seemingly do not fit into the ordinary system of “neutral” conflicts-of-laws rules.

Overriding Mandatory Rules and Public Law

Hemler demonstrates that the isolation of overriding mandatory provisions arises from the tendency to implicitly identify these rules with national public law. He shows how this equation leads to the application of principles (seemingly) governing conflicts of public law rules. Up to now, it was widely assumed that the application of foreign public law would impossible, as it would amount to allowing a foreign state to exercise power on the national territory of another. Hemler criticises this assumption by explaining the general methodology of conflicts-of-laws rules. Following a theory developed by Boris Schinkels, he divides each legal rule analytically into a “rational” and an “imperative” element. The rational element describes a universal idea needed for the proper resolution of a legal conflict. An example of the rational element is the written form requirement for certain contracts, e.g. those concerning the transfer of land. The imperative element, in contrast, describes the state’s order to apply the rule. In the example of the written form requirement, the imperative element would be the legislator’s intent relating to the enforcement of the requirement to all land situated on its country’s territory.

Within this structure of legal provisions, Hemler views the position of autonomous conflicts-of-laws rules as follows: Since citizens have a right to decide for themselves which rules are to be applied in their country, its courts cannot just bow to the will of another state. On the other hand, it would go too far to exclude the application of foreign law altogether. Rather, the forum issues its own imperative command regarding any rules of foreign law, which leads to the exclusive applicability of the foreign rule’s rational element. The disregard of the foreign imperative is a direct consequence of the modern, autonomous structure of conflicts of laws. Hence, courts only transpose the foreign “idea of what ought to be” without any elements of foreign sovereignty. This isolated application of the foreign rational element and its combination with a domestic imperative element leads to the creation of a domestic legal norm with a foreign ratio (a “synthesised” legal norm, so to speak).

Since the applied foreign rational element is stripped of any element of the exercise of foreign sovereignty, Hemler argues that the application of foreign law does not conflict with the sovereignty of the court’s country or that of a third country whose law is applicable under ordinary rules of private international law. Hence his conclusion that courts may apply foreign public law without any restrictions, especially without the need of the foreign law being “neutral” or “pre-state”.

No Need for Special Conflicts Rules Regarding Overriding Mandatory Provisions

Going further, Hemler shows that there are no convincing reasons to treat overriding mandatory provisions differently from other norms. In particular, he opines that these provisions do not call for a separate system of conflicts-of-laws rules. Hemler shows that the whole category of overriding mandatory provisions can be dispensed with and that one should instead focus on the development of a more differentiated set of conflicts-of-laws rules. He explains in detail how such special conflicts-of laws-rules are to be developed.

A New Understanding of the Public Policy Exception

His findings allow Hemler to shed also some light on the public policy exception. Given that every application of foreign law leads to a synthesised legal norm of the forum, he concludes that the public policy exception can actually be understood as a constitutional control device regarding “synthesised” law. In Hemler’s view, such an understanding facilitates the inclusion of numerous new phenomena into the methodology of private international law.


As this short overview demonstrates, this is a though-provoking book. Overriding mandatory provisions have so far played the role of a black box in private international law. After many failed attempts to “domesticise” these rules, this is the most serious theory to integrate these rules into the edifice of conflict-of-laws theory. Particularly striking is the breadth of the author’s perspective, which is not limited to overriding mandatory rules, but also includes the role of constitutional law, public law in general as well as the public policy exception. For the interested reader, this book is a good reason to brush up their German or start to learn it!

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