These Principles set forth general rules for international commercial contracts.

They shall be applied when the parties have agreed that their contract be governed by them (*).

They may be applied when the parties have agreed that their contract be governed by general principles of law, the lex mercatoria or the like.

They may be applied when the parties have not chosen any law to govern their contract.

They may be used to interpret or supplement international uniform law instruments.

They may be used to interpret or supplement domestic law.

They may serve as a model for national and international legislators.


(*)Parties wishing to provide that their agreement be governed by the Principles might use the following words, adding any desired exceptions and modifications:
“This contract shall be governed by the UNIDROIT Principles (2010) [except as to Articles …]”.

Parties wishing to provide in addition for the application of the law of a particular jurisdiction might use the following words:
“This contract shall be governed by the UNIDROIT Principles (2010) [except as to Articles …], supplemented when necessary by the law of [jurisdiction X]”.



The Principles set forth general rules which are basically conceived for “international commercial contracts”.


1. “International” contracts

The international character of a contract may be defined in a great variety of ways. The solutions adopted in both national and international legislation range from a reference to the place of business or habitual residence of the parties in different countries to the adoption of more general criteria such as the contract having “significant connections with more than one State”, “involving a choice between the laws of different States”, or “affecting the interests of international trade”.

The Principles do not expressly lay down any of these criteria. The assumption, however, is that the concept of “international” contracts should be given the broadest possible interpretation, so as ultimately to exclude only those situations where no international element at all is involved, i.e. where all the relevant elements of the contract in question are connected with one country only.


2. “Commercial” contracts

The restriction to “commercial” contracts is in no way intended to take over the distinction traditionally made in some legal systems between “civil” and “commercial” parties and/or transactions, i.e. to make the application of the Principles dependent on whether the parties have the formal status of “merchants” (commerçantsKaufleute) and/or the transaction is commercial in nature. The idea is rather that of excluding from the scope of the Principles so-called “consumer transactions” which are within the various legal systems being increasingly subjected to special rules, mostly of a mandatory character, aimed at protecting the consumer, i.e. a party who enters into the contract otherwise than in the course of its trade or profession.

The criteria adopted at both national and international level also vary with respect to the distinction between consumer and non-consumer contracts. The Principles do not provide any express definition, but the assumption is that the concept of “commercial” contracts should be understood in the broadest possible sense, so as to include not only trade transactions for the supply or exchange of goods or services, but also other types of economic transactions, such as investment and/or concession agreements, contracts for professional services, etc.


3. The Principles and domestic contracts between private persons

Notwithstanding the fact that the Principles are conceived for international commercial contracts, there is nothing to prevent private persons from agreeing to apply the Principles to a purely domestic contract. Any such agreement would however be subject to the mandatory rules of the domestic law governing the contract.


4. The Principles as rules of law governing the contract

a. Express choice by the parties

As the Principles represent a system of principles and rules of contract law which are common to existing national legal systems or best adapted to the special requirements of international commercial transactions, there might be good reasons for the parties to choose them expressly as the rules of law governing their contract. In so doing the parties may refer to the Principles exclusively or in conjunction with a particular domestic law which should apply to issues not covered by the Principles (see the Model Clause in the footnote to the second paragraph of the Preamble).Parties who wish to choose the Principles as the rules of law governing their contract are well advised to combine such a choice of law clause with an arbitration agreement.

The reason for this is that the freedom of choice of the parties in designating the law governing their contract is traditionally limited to national laws. Therefore, a reference by the parties to the Principles will normally be considered to be a mere agreement to incorporate them in the contract, while the law governing the contract will still have to be determined on the basis of the private international law rules of the forum. As a result, the Principles will bind the parties only to the extent that they do not affect the rules of the applicable law from which the parties may not derogate (see Comment 3 on Article 1.4).

The situation is different if the parties agree to submit disputes arising from their contract to arbitration. Arbitrators are not necessarily bound by a particular domestic law. This is self-evident if they are authorised by the parties to act as amiable compositeurs or ex aequo et bono. But even in the absence of such an authorisation parties are generally permitted to choose “rules of law” other than national laws on which the arbitrators are to base their decisions (see in particular Article 28(1) of the 1985 UNCITRAL Model Law on International Commercial Arbitration; see also Article 42(1) of the 1965 Convention on the Settlement of Investment Disputes between States and Nationals of other States (ICSID Convention)).

In line with this approach, the parties would be free to choose the Principles as the “rules of law” according to which the arbitrators would decide the dispute, with the result that the Principles would apply to the exclusion of any particular national law, subject only to the application of those rules of domestic law which are mandatory irrespective of which law governs the contract (see Comment 4 on Article 1.4).

In disputes falling under the ICSID Convention, the Principles might even be applicable to the exclusion of any domestic rule of law.

b. The Principles applied as a manifestation of “general principles of law”, the “lex mercatoria” or the like referred to in the contract

Parties to international commercial contracts who cannot agree on the choice of a particular domestic law as the law applicable to their contract sometimes provide that it shall be governed by the “general principles of law”, by the “usages and customs of international trade”, by the lex mercatoria, etc.

Hitherto, such reference by the parties to not better identified principles and rules of a supranational or transnational character has been criticised, among other grounds, because of the extreme vagueness of such concepts. In order to avoid, or at least to reduce considerably, the uncertainty accompanying the use of such rather vague concepts, it might be advisable, in order to determine their content, to have recourse to a systematic and well-defined set of rules such as the Principles.

c. The Principles applied in the absence of any choice of law by the parties

The Principles may however be applied even if the contract is silent as to the applicable law. If the parties have not chosen the law governing their contract, it has to be determined on the basis of the relevant rules of private international law. In the context of international commercial arbitration such rules are very flexible, permitting arbitral tribunals to apply “the rules of law which they determine to be appropriate” (see e.g. Article 17(1) of the 1998 Rules of Arbitration of the International Chamber of Commerce; Article 24(1) of the Rules of the Arbitration Institute of the Stockholm Chamber of Commerce). Normally arbitral tribunals will apply a particular domestic law as the proper law of the contract, yet exceptionally they may resort to a-national or supra-national rules such as the Principles. This may occur when it can be inferred from the circumstances that the parties intended to exclude the application of any domestic law (e.g. where one of the parties is a State or a government agency and both parties have made it clear that neither would accept the application of the other’s domestic law or that of a third country), or when the contract presents connecting factors with many countries none of which is predominant enough to justify the application of one domestic law to the exclusion of all the others.


5. The Principles as a means of interpreting and supplementing international uniform law instruments

International uniform law instruments may give rise to questions concerning the precise meaning of their individual provisions and may present gaps.

Traditionally international uniform law has been interpreted on the basis of, and supplemented by, principles and criteria of domestic law, be it the law of the forum or that which would, according to the relevant rules of private international law, be applicable in the absence of an international uniform law.

Recently, both courts and arbitral tribunals have increasingly abandoned such a “conflictual” approach, seeking instead to interpret and supplement international uniform law by reference to autonomous and internationally uniform principles and criteria. This approach, expressly sanctioned in recent conventions (see, e.g., Art. 7 of the 1980 UN Convention on Contracts for the International Sale of Goods (CISG)), is based on the assumption that international uniform law, even after its incorporation into the various national legal systems, only formally becomes an integrated part of the latter, whereas from a substantive point of view it does not lose its original character of a special body of law autonomously developed at international level and intended to be applied in a uniform manner throughout the world.
Until now, such autonomous principles and criteria for the interpretation and supplementing of international uniform law instruments have had to be found in each single case by the judges and arbitrators themselves on the basis of a comparative survey of the solutions adopted in the different national legal systems. The Principles could considerably facilitate their task in this respect.


6. The Principles as a means of interpreting and supplementing domestic law

The Principles may also be used to interpret and supplement domestic law. In applying a particular domestic law, courts and arbitral tribunals may be faced with doubts as to the proper solution to be adopted under that law, either because different alternatives are available or because there seem to be no specific solutions at all. Especially where the dispute relates to an international commercial contract, it may be advisable to resort to the Principles as a source of inspiration. By so doing the domestic law in question would be interpreted and supplemented in accordance with internationally accepted standards and/or the special needs of cross-border trade relationships.


7. The Principles as a model for national and international legislators

In view of their intrinsic merits the Principles may in addition serve as a model to national and international law-makers for the drafting of legislation in the field of general contract law or with respect to special types of transaction. At a national level, the Principles may be particularly useful to those countries which lack a developed body of legal rules relating to contracts and which intend to update their law, at least with respect to foreign economic relationships, to current international standards. Not too different is the situation of those countries with a well-defined legal system, but which after the recent dramatic changes in their socio-political structure have an urgent need to rewrite their laws, in particular those relating to economic and business activities.

At an international level the Principles could become an important term of reference for the drafting of conventions and model laws.
So far the terminology used to express the same concept differs considerably from one instrument to another, with the obvious risk of misunderstandings and misinterpretations. Such inconsistencies could be avoided if the terminology of the Principles were to be adopted as an international uniform glossary.


8. Other possible uses of the Principles

The list set out in the Preamble of the different ways in which the Principles may be used is not exhaustive.

Thus, the Principles may also serve as a guide for drafting contracts. In particular the Principles facilitate the identification of the issues to be addressed in the contract and provide a neutral legal terminology equally understandable by all the parties involved. Such a use of the Principles is enhanced by the fact that they are available in a large number of languages.

The Principles may also be used as a substitute for the domestic law otherwise applicable. This is the case whenever it proves impossible or extremely difficult to establish the relevant rule of that particular domestic law with respect to a specific issue, i.e. it would entail disproportionate efforts and/or costs. The reasons for this generally lie in the special character of the legal sources of the domestic law in question and/or the cost of accessing them.

Furthermore, the Principles may be used as course material in universities and law schools, thereby promoting the teaching of contract law on a truly comparative basis.