The most talked-about purpose of the UNIDROIT Principles of International and Commercial Contracts (PICC) is their applicability as the law chosen by the parties. However, focusing on this purpose in isolation is erroneous. The PICC are not a good candidate for a chosen law - they are conceived not as a result of the exercise of freedom of contract, but instead as a framework to enable such exercise. Their real potential is to serve as objective law - as the general part of transnational contract law.
This is obvious in practice. Actually, choice of the PICC is widely possible. National courts accept their incorporation into the contract; arbitrators frequently accept their choice as applicable law. However, in practice, the PICC are rarely chosen. The most important reason is that they are incomplete. They contain no rules on specific contracts. Further, they refer to national law for mandatory rules and for standards of illegality and immorality. This makes their choice unattractive.
The nature of the PICC is much closer to that of the U.S. Restatement of the law. The U.S. Restatement becomes applicable not through party choice but rather as an articulation of background law. Actually, this describes the way in which the PICC are typically used in practice.
This use as background law cannot be justified with an asserted legal nature of the PICC (their »law function«). Rather, the use is justified insofar as they fulfill two other functions: the »restatement function« (PICC as description of a common core of legal rules) and the »model function« (PICC as model for a superior law).
From a choice-of-law perspective, such use cannot be justified under traditional European choice of law, which designates legal orders, not incomplete codifications, as applicable.
By contrast, application could be justified under U.S. choice of law. Under the governmental interest analysis, the PICC could be applicable to situations in which no state is interested in the application of its own law. Their international character qualifies the PICC for the Restatement (2d) Conflict of laws. Finally, for the better-law theory, according to which the substantive quality of a law is a criterion for choice of law, the PICC are a candidate insofar as they perform a model function.
In result, the PICC are comparable to general common law or the ius commune, within which regulatory rules of national, supranational and international origin act like islands.
Altogether, this results in a complex picture of transnational contract law, which combines national, international and non-national rules. The PICC can be no more, but no less, than a general part of this contract law.
Ralf Michaels, Umdenken Für Die UNIDROIT - Prinzipien: Vom Rechtswahlstatut Zum Allgemeinen Teil Des Transnationalen Vertragsrechts [Rethinking the UNIDROIT Principles: From a Law to Be Chosen by the Parties Towards a General Part of Transnational Contract Law], 73 Zeitschrift für ausländisches und internationales Privatrecht 866-888 (2009)
Library of Congress Subject Headings
UNIDROIT principles of international commercial contracts 2004, International Institute for the Unification of Private Law