Principles and Rules in the Evolving European Law of Contract: From the PECL to the SECL, and Beyond

9 European Review of Contract Law 1-37

37 Pages Posted: 6 Jan 2014 Last revised: 19 Jul 2019

See all articles by Yehuda Adar

Yehuda Adar

University of Haifa

Pietro Sirena

Bocconi University - Bocconi Law Department

Date Written: 2013


Legal principles play an important role in any system of law. Following the European Court of Justice, the treaties of the European Union have embraced the concept of “principles of law”, mainly as a means to guarantee individual and human rights in public and constitutional law. More recently, however, the ECJ has come to recognize as “general principles” private law and contract law norms and values. Furthermore, the notion of “principles” has played a key role in impressive unification projects which aimed to promote harmonization of national contract laws in Europe, such as the PECL (“Principles of European Contract Law”) and the DCFR (Draft Common Frame of Reference). The proposed Common European Sales Law (CESL) also opens with a separate chapter dedicated to “General Principles” of contract law.

The article invites the reader to think more carefully and critically about the role played by alleged “principles” in the law generally, and in the evolving European law of contract in particular. Part II points out the instability and vagueness of the concept of a legal “principle”. Part III presents an original theoretical model which aims to reduce the inherent vagueness surrounding the concept and the distinction between legal rules and legal principles. The model suggests that while principles do often differ from rules in other respects as well (e.g., in their substantive content or analytical structure), these common distinctions fail to capture the most essential difference between principles and rules, which lies in their sharply distinct political function. Part IV applies this general thesis to the multi-level constitutional architecture of European law, coming to the conclusion that the principles of European private law are those common core norms which are shared by the laws of most Member States (ius commune Europaeum). Part V applies and illustrates this claim on the various instruments by which the Union has attempted to promoted the unification of contract law around Europe. Part VI concludes by claiming that the European principles, including that of subsidiarity, are best understood as a balancing device by which the Union adjusts the level of regulation between legislature and courts on the one hand, and between the supranational and national powers on the other.

Keywords: principles of law, principles and rules, European contract law, PECL, PICC, DCFR

JEL Classification: K12, K33

Suggested Citation

Adar, Yehuda and Sirena, Pietro, Principles and Rules in the Evolving European Law of Contract: From the PECL to the SECL, and Beyond (2013). 9 European Review of Contract Law 1-37, Available at SSRN:

Yehuda Adar (Contact Author)

University of Haifa ( email )

Mount Carmel
Haifa, 31905
+04 8240633 (Phone)


Pietro Sirena

Bocconi University - Bocconi Law Department ( email )


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