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van Houtte, Hans, Les Principes UNIDROIT et lArbitrage Commercial International, in: ICC (ed.), The UNIDROIT Principles for International Commercial Contracts - A New Lex Mercatoria?, Paris 1995, at 181 et seq.

van Houtte, Hans, Les Principes UNIDROIT et lArbitrage Commercial International, in: ICC (ed.), The UNIDROIT Principles for International Commercial Contracts - A New Lex Mercatoria?, Paris 1995, at 181 et seq.
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Table of Contents

The UNIDROIT Principles of International Commercial Contracts (hereafter UNIDROIT Principles) address themselves equally to both judicial courts and to commercial arbitration tribunals. Indeed, Article 1.10 (Definitions) states: "In these Principles "court" includes an arbitral tribunal". However, as it is also stressed in the Preamble to the Principles, international commercial arbitration appears to be particularly important for the UNIDROIT Principles. Something which is equally important is the fact that these Principles can also be relevant to international commercial arbitration.

Part I will examine the relevante of arbitration to the UNIDROIT Principles; Part II' will focus an the relevante of the Principles to arbitration.


1. Arbitration is said to elevate the UNIDROIT Principles to a national law

The UNIDROIT Principles set forth general rules for international commercial contracts. However, as long as disputes over contracts are settled by a national court instead of by an international arbitration tribunal, the UNIDROIT Principles can only play a complementary rote besides the national contract law. Indeed, for national courts a contract has to be governed by a national legal system. Consequently, in the eyes of national courts, parties who agree that the Principles will govern their contract can merely "incorporate" these principles into their contract which otherwise remains governed by national law.

The UNIDROIT Principles do not haveto play this secondary role when contract disputes must be submittel to international commercial arbitration. In the event that the arbitrators are allowed to decide as amiable compositeurs, i.e. ex aequo et bono, they do not haveto apply a specific national law and can thus use the UNIDROIT Principles as an autonomous standard. However, it also has become widely accepted that even international commercial arbitrators who are not amiable compositeurs do not haveto apply a specific national legal system but may apply anational rules (such as general principles of law or the lex mercatoria). In that event they may consider the UNIDROIT Principles to be part of these anational rules. Besides, the drafters of the UNIDROIT Principles haveclaimed that the Principles are indeed part of the general principles of law or the lex mercatoria1 .

Three critical observations.

Firstly, the UNIDROIT Principles not only refer to national law for issues of capacity and form but they yield to all relevant mandatory rules of domestic law2 . The anational ambitions of the UNIDROIT Principles are difficult to reconcile with these many references to domestic law.


Secondly, it is not up to the Principles to advance themselves as general principles of law or as lex mercatoria. As general principles of law the UNIDROIT text will only be accepted when the legal community and not merely the some twenty drafters of the UNIDROIT text, no matter how skilled and reputed these lawyers may be, has recognized that the UNIDROIT document states principles which underlie most legal systems and are generally accepted. In fact some UNIDROIT rules are certainly too specific to be perceived as such3 . The UNIDROIT standards will only be part of the lex mercatoria if they are recognized as such by the business community and its arbitrators. Since the UNIDROIT Principles have just been launched, it is too early to assess this possibility.

Thirdly, it is as yet uncertain what the UNIDROIT Principles may contribute to the general principles of law or to the lex mercatoria. For the UNIDROIT drafters, the Principles are useful because they give the extremely vague concepts from the general principles of law and the lex mercatoria a well defined content4 . Many Principles, however, remain rather vague and where other Principles become more specific it may be questioned whether they still reflect the widely accepted standards from the general principles of law or from the lex mercatoria.


UNIDROIT proposes principles - not rules - of international contract law.

The distinction between "principles" and "rules" is well established in legal theory. Roscoe Pound and Geny explored these notions on both sides of the Atlantic in the twenties5 . Nowadays the differente between "principles" and "rules" is still essential for many legal philosophers, such as e.g. Dworkin6 .

Legal principles are as good as statement of a law as are legal rules7 . It has been said that legal principles differ from legal rules by being more general. In fact, however, legal principles have different degrees of generality and some may be quite specific. A more essential difference between principles and rules is that principles offer fundamental standards which may be in conflict when applied to a specific case, while rules apply in an all-or-nothing fashion. Moreover, principles have to be balanced against each other whereby some principles will receive more weight than others8 . Furthermore, principles are subject to continuous debate on their justification and scope. A rule, on the other hand, if it applies, fully determines the 185 situation. Rules do not have to be weighed against one another. They are strictly adhered to without question.

The business community is not governed by a "rulebook"9 but rather by principles. Parties to an international contract submit themselves to the legal principles of international trade and, at the saure time, reserve the right to adapt these principles to the case at stake. In this sense, their adherence to the UNIDROIT Principles of International Contract Law appears to be a most natural choice. But principles imply that a third party exists to determine the respective scope of the various relevant standards and balance them against each other when the parties cannot come to an agreement an these points. For the UNIDROIT Principles this third party should preferably not be a state court, but an arbitration tribunal, which is much more closely in touch wich the international Business community and its values and interests. Thus, arbitrators wïll be the natural authority for the interpretation and application of the UNIDROIT Principles.


The UNIDROIT Principles of International Commercial Contracts refer to many "notions" and "standards", which have no specific meaning but whose content depends an the context in which they are applied. Chaim Perelman would name these notions "notions à contenu variable en droit"10 . Many of these "notions" have already been the subject matter of numerous arbitration proceedings an international commercial contracts. Arbitral awards thus may give body to the notions of the UNIDROIT Principles. However, Information about awards is often difficult to obtain. Awards are generally not published. Moreover they "display a multitude of approaches which ... do not provide the firm band of settled case law". Nevertheless, awards still may "offer useful guidance"11 . Indeed, the similarity in the facts, the familiarity of the arbitrators with the business community and the quality of the arbitration panels make many awards an authoritative precedent in interpreting the UNIDROIT Principles.

There are many "notions à contenu variable" in the UNIDROIT Principles. If parties, judges or arbitrators have no point of reference for these notions, they risk giving the Principles a rather subjective and occasional meaning. Application of the Principles would then result in much uncertainty in spite of the uniformity which the Principles aim at. However, the Principles reflect arbitration practice. Their "notions à contenu variable" receive a more specific meaning through arbitration awards. With a vast arbitration practice as reference, the Principles become a more stable standard. A few examples will illustrate how notions from the UNIDROIT Principles receive a more specific meaning from international arbitration practice.


1. Usages

Under Article 1.8, international trade usages that are widely known and regularly observed in the particular trade bind the contracting parties12 . Under Article 4.3 these usages are relevant in interpreting the contract13 .

The best sources of knowledge about such international trade usages and practices are the international arbitration awards which settle disputes from the specific trade. Such awards may come from arbitration institutions of trade associations, such as GAFTA (Grain and Feed Trade Association), which have a truly international Field of Operation, or from arbitrators whose expertise and familiarity with international trade is internationally recognized.

It is less certain if usages, formulated by domestic arbitration Panels or by institutions which generally settle domestic disputes and only occasionally a dispute with a foreign party, reflect international usages to the same extent. However, domestic institutions and arbitration panels can give insight into local usages, on for example commodity markets or ports, which are relevant to the modalities of Performance14 .

2. Good faith and fair dealing

Article 1.7 enounces a fundamental idea, which also underlies many other Principles15 , namely that "Parties are under a general obligation to act in good faith and fair dealing in international trade". By looking to international trade for good faith and fairness, the drafters made it clear that international trade standards may be different than domestic standards. In other words, fairness and good faith on the domestic level is not necessarily fairness and good faith in international trade. Domestic standards only become international standards if they are shared by other countries and/or if they are applicable in international transactions16 . The drafters even recognized that good faith and fairness may be different from one trade sector to another as standards and business practices may vary substantially between different trades.

Many awards, which give judgments on the question of whether parties have acted fairly and in good faith in a multitude of situations and in variety of trades, can be of guidance in interpreting these concepts.


3. Reasonableness

Some twenty UNIDROIT Principles17 refer to the standard of "reasonableness", the textbook example of a "notion à contenu variable"18 . Many past awards have indicated what arbitrators have considered to be reasonable in certain circumstances. In fact, a "reasonable" solution is what most awards end up with. The arbitrators' views may be used as guidelines in applying the reasonableness standard of the UNIDROIT Principles.

4. Hardship

How arbitral awards can give a more specific meaning to the UNIDROIT Principles may be illustrated with the UNIDROIT rules on hardship (Section 6 - Articles 6.2.1, 6.2.2 and 6.2.3).

(a) Pacta sunt servanda?

As already stated, principles may be conflicting and have then to be weighed against one another. In a case of hardship, two contradictory UNIDROIT Principles surely have to be balanced. One UNIDROIT Principle maintains the sanctity of contract in spite of hardship: "Where the performance of a contract becomes more onerous for one of the parties, that party is nevertheless bound to perform its obligation..." (Article 6.2.1). However, alter this Statement of principle, the UNIDROIT text opens all sorts of possibilities for remedies because of hardship: indeed, Article 6.2.1 has consecrated the sanctity of contract "... subject to the following provisions on hardship".Accordingly, the UNIDROIT Principles stick less to a strict "pacta sunt servanda" than other international texts which also claim to reflect international business practice (such as the Vienna Convention on International Sales of Goods which does not provide a remedy for "economic hardship"19 ). The proceeding Articles on hardship contain a few criteria to determine when hardship will indeed affect the contract terms and to what remedy it may lead. These criteria, however, remain rather general. The official Comment which seeks to clarify these criteria, moreover, remains vague. Arbitration practice gives a more specific content to these criteria.


Of course arbitrators have often confirmed that contract terms must be respected20 . However, the issue is not so much whether contract terms have to be respected, but to what extent they must be respected. In other words what is the scope of the contractual obligations ?

(b) Disruption of Balance

Under the UNIDROIT Principles parties are no longer bound by the terms of the contract as such "where the occurrence of events alters the equilibrium of the contract either because the cost of a party's performance has increased or because the value of the performance a party receives has diminished" (Article 6.2.2). Arbitral practice is relevant in illustrating the different elements of this rule:


Article 6.2.2 starts from the presupposition that there is an "equilibrium" in the contract. This notion of "equilibrium" between the performances has also been fundamental in many awards. As it has been stated in an ICC award from 1975:


The original balance between the contractual performances can be fundamentally disturbed when the cost of a party's performance has increased. The Comments specify that this may, for example, occur because of a dramatic rise in the price of raw materials necessary for the production of the goods or the rendering of services, or because of the introduction of new safety regulations ,requiring far more expensive production procedures22 . Arbitration awards may give examples of such situations23 .


It may also happen that the value of the performance a party receives has so diminished that the respective contractual performances are no longer in balance. As the Comments mention, market conditions can change so drastically that the performance has lost all value; or dramatic inflation can inflate the contract price; or, an export embargo can make a contract meaningless. Awards may be used as guidelines to assess the hardship. Indeed, awards have considered the impact of changes in market conditions on the contract24 . Other awards have examined when currency depreciation would justify relief25 . Other awards have decided whether economic embargo legislation which prevented export also 189 affected contracts under which the goods to be exported were acquired26 . These awards are relevant precedents in understanding Article 6.2.2.

(c) Fundamental change?

Article 6.2,2 of the UNIDROIT Principles does not state when the equilibrium of the contract has been fundamentally altered. The Comments to the Principles play it safe when they state:

"whether an alteration is "fundamental" in a given case will of course depend upon the circumstances".

Whether equilibrium has been so greatly disturbed that a remedy must be granted, is left to the appreciation of the parties and finally to the court or to the arbitrator. Arbitrators have often been rather reluctant to intervene in the contract on the basis of hardship where the parties did not provide for this possibility, for instance by including a hardship clause:

"Considérant au surplus que le principe rebus sic stantibus ne peut recevoir son application en l'espèce. Il convient en effet de ne retenir cette notion qu'avec réserve et prudence, surtout lorsque l'intention des parties a été clairement exprimée dans un contrat. La précaution s'impose d'autant plus lorsqu'il s'agit de transactions internationales où en général les parties ont conscience des risques qui peuvent survenir et sont ainsi à même de les formuler de manière précise"27 .

In another ICC award the arbitrators refused to intervene because: "otherwise, any business transaction would be exposed to uncertainty, or even be rendered impossible altogether, whenever the mutual covenants are not performed at the time at which the contract is concluded"28 .

As yet another ICC arbitrator stated, a change in circumstances has to be understood very strictly:

"The principle rebus sic stantibus is universally considered as being of strict and narrow interpretation, as a dangerous exception to the principle of sanctity of contracts. Whatever opinion or interpretation lawyers of different countries may have about the "concept" of changed circumstances as an excuse for non-performance, they will doubtless agree on the necessity to limit the application of the so-called "doctrine rebus sic stantibus" (sometimes referred to as "frustration", "force majeure", "imprévision", and the like) to cases where compelling reasons justify it"29 .


Arbitrators are generally reluctant to intervene into a contract because of Inflation and currency depreciation in the absence of a specific currency depreciation clause30 . As a Hamburg arbitrators stated:

"As a matter of principle, every money debt is a debt in value with the result that only the nominal value of the currency is due and payment of the depreciated money releases the debt"31 .

(d) Mathematical criteria

The Comments relating to Article 6.2. become more outspoken when they state:

"If, however, the performances are capable of precise measurement in monetary terms, an alteration amounting to 50% or more of the cost or value of the performance is likely to amount to a "fundamental" alteration".

Arbitral practice confirms that no relief was granted when the market price for steel had increased by a mere 13% between the time the contract for the sale of steel was concluded and the time of delivery32 or when the profit in a long-term concession was for six wartime years, which was far less then expected33 . However, to return to the 50% criterion the Comments propose: no award is known to the present writer where arbitrators have granted relief (in the absence of a hardship clause) merely because the costs or value of the Performance had increased by 50% compared to what had been agreed in the contract.

(e) No assumption of risk of change in circumstances

UNIDROIT - Article 6.2.2 puts a few conditions on the possibility of the party invoking hardship. In particular for one of these conditions (the condition that the disadvantaged party did not assume the risk of the events), arbitration practice is particularly relevant. Indeed, arbitrators often indicate that parties to international contracts must have been aware of the risks. If parties do not want to assume these risks, then they have to include a hardship clause in the contract34 and arbitrators will take into account such a hardship clause. When Parties refrain from including a hardship clause, arbitrators, however, will often be inclined to disregard the changed circumstances35 .


As ICC arbitrators stated:

"... dans les transactions internationales ... il est en général plus improbable que les parties n'aient pas été conscientes du risque des impondérables éloignées ou capables de la formule de façon précise"36 .

Or as they decided in another case:

"Caution is especially called for, moreover, in international transactions where it is generally much less likely that the parties have been unaware of the risk of a remote contingency or unable to formulate it precisely"37 .

In fact arbitrators sometimes distinguish between speculative and non-speculative contracts38 . Where parties did not enter into a contract with speculative intentions, relief for changed circumstances should be more easily granted39 . ICC arbitrators have based their relief for changed circumstances on the non-speculative nature of the contract:

"C'est une règle de la lex mercatoria que les prestations restent équilibrées Sur le plan financier et nier ce principe reviendrait à faire du contrat commercial un contrat aléatoire fondé sur la speculation ou le hasard"40 .

Arbitrators of the Japan Shipping Exchange similarly refused to grant a remedy because the contract was speculative:

"In contracts such as the present one, of a commercial base, where the cost may be set arbitrarily and which has a speculative nature to a degree, it is not possible to decide that there existed a situation to which a so-called change in situation principle could be applied"41 .

However, even when the contract is speculative by nature and the parties have contemplated certain risks, good faith prevents a party from insisting on contract performance as originally agreed when such a demand would be clearly abusive in the light of the substantial change in circumstances. Such was the decision reached in an ICC arbitration under Swiss law42 .


(f) Remedies: contract termination or adaptation

Under UNIDROIT Principle Acticle 6.2.3, if there is hardship the contract should be renegotiated; if renegotiations remain unsuccessful, the courts or arbitrators may, "if reasonable"; either terminate the contract on the terms they deem appropriate or adapt the contract to restore the balance. In other words, judges and arbitrators have discretionary power to decide what they deem fit. Arbitration practice offers them some guidance in their decision.

Sometimes arbitrators have only been willing to intervene if otherwise one party would be unjustly enriched at the expense of the other party43 or to spread the burden of the change of circumstances equally between both parties44 .

Article 6.2.3 of the UNIDROIT Principles provides not only for contract termination, but also for contract adaptation in case of hardship. However, in some legal systems, such as those of England45 and Belgium46 , courts will refuse to adapt the contract terms to changed circumstances or to substitute new terms more suitable to the changed situation. In other legal systems, such as the German47 , the Dutch48 or the Japanese ones49 , judges appear to be less reluctant to adjust contracts to take into account the changed circumstances. If parties envisage contract adaptation in case of hardship, they should provide for such adaptation and specify its conditions in a detailed hardship clause in the contract. Furthermore, to be on the safe side they should include an arbitration clause in their contract so that in case of hardship the contract may be adapted by an arbitrator, who would be less reluctant than some judges to adapt the contract terms.

5. Temporary or definite impossibility of performance

An area related to hardship, where arbitration practice can offer guidance to the Interpretation of the UNIDROIT Principles, is "force majeure".

Article 7.1.7(2) of the Principles, for instance, provides that temporary impossibility of performance may only excuse performance for such a period: the contract has to be 193 resumed as soon as performance becomes possible again. It is, however, sometimes unclear whether an impossibility of performance is temporary or definite. This issue has been raised in a few arbitration proceedings, for instance concerning the Impact of the UN economic sanctions against Iraq an trade contracts. The more specific question was whether the UN sanctions constituted a temporary impossibility, which only suspends contract performance, or a definite impossibility, which puts an end to the contract. Indeed, on the one hand, these sanctions are only temporary as they will be lifted whenever the UN considers that they are no longer required because Iraq complies with the conditions the UN has imposed. On the other hand, these sanctions were introduced in 1990 and have blocked contract performance for more than four years. In one case an arbitrator decided that alter two years of economic sanctions, the impossibility to perform had become definitive:

"Further, it seems to the Arbitrator that the impossibility to perform under contracts promoting forbidden activities towards Iraq, which originally could be considered temporary, must now - two years after - be considered definitive, taking into account that the medio tempore circumstances in the relationship with Iraqi parties have fundamentally changed, that it is still impossible to foresee if and when full normalization shall be reached in the relationship with the Iraqi State and that it shall be necessary, if normalization shall be reached in the near or far future, to renegotiate all contracts"50 .

This award undoubtedly will constitute a precedent in clarifying the dividing line between temporary and definite impossibility of performance as provided under UNIDROIT Principle Article 7.1.7(2).


Many UNIDROIT Principles are useful for arbitration practice.


Article 7.5.3 confirms what is generally accepted, namely that the termination of the contract does not affect the arbitration clause which remains binding even after termination. The UNIDROIT Principles do not, however, contain a wider recognition of the autonomous character of the arbitration clause. For instance they do not state that the arbitration clause can remain valid, even if the contract of which it is part is null and void.


Article 2.11 covers the issue of modified acceptance: if a reply to an offer materially alters the terms of the offer, it constitutes a counter-offer which needs to be accepted on its return. The Comments indicate that the inclusion of an arbitration clause in the acceptance normally constitutes a material modification. However, this need not necessarily be the case: when an arbitration clause is commonly used in the trade sector concerned, it should not come as a surprise to the offeror and would thus not substantially alter his offer51 . If the offeror would not object to the arbitration clause in that case, he would be bound by it. These principles, which are also contained in the Vienna Convention on 194 international Sales52 , have already been recognized in some national arbitration laws53 . Their inclusion in the UNIDROIT Principles will enhance their wider acceptance.


It is not commonly accepted that arbitrators can adapt contract terms. The UNIDROIT Principles confirm the idea that arbitrators are entitled to do so. Under Article 3.11 a party may avoid the contract or a specific contract provision if it gave the other party an excessive advantage at the time of conclusion of the contract; however, that party may also request the arbitrators "to adapt the contract or term in order to make it accord with reasonable standards of fair dealing". Likewise, under Article 6.2.3, arbitrators can adapt contract terms in case of hardship. The UNIDROIT Principles may thus spread the idea that arbitrators are also entitled to adapt contract terms and introduce this idea into national law, where necessary.


Article 7.2.4 allows courts and arbitrators to impose a judicial penalty in the case where a party will not obey their order. Judicial penalties are, however, not generally accepted in arbitration. The extent to which the drafters of the UNIDROIT Principles are in favour of allowing judicial penalties in arbitration follows from the Comments:


One of the most unsettled issues in arbitration concerns the interest rate by which the arbitrators will determine the interest on an unpaid debt. White some arbitrators apply the statutory interest from the proper law of the contract under which the payment had to be made, other arbitrators apply the statutory interest from the country of the currency in which the debt is formulated. Some others use the statutory interest of the creditor's country or from the debtor's country and others award "reasonable commercial" interest55 . Article 7.4.9 of the UNIDROIT Principle contains an elaborate provision an interest rates: 195

"(2) The rate of interest shall be the average bank short-term lending rate to prime borrowers prevailing for the currency of payment at the place for payment, or where no such rate exists at that place, then the same rate in the State of the currency of payment. In the absence of such a rate at either place the rate of interest shall be the appropriate rate fixed by the law of the State of the currency of payment."


Undoubtedly the UNIDROIT Principles and arbitration practice will interact. The UNIDROIT Principles will rely heavily on arbitration for the Interpretation of its "notions à contenu variable". Arbitration will apply the Principles in its decision-making.

1 Preamble, paragraph 3: "(These Principles) may be applied when the parties have agreed that their contract be governed by "general principles of law", the "lex mercatoria" or the like".
2 Articles 1.2, 1.4 and 3.1.
3 See e.g. the detailed and innovative rules on interest for failure to pay (Article 7.4.9), and on the currency in which to assess damages (Article 7.4.12).
4 Preambule, Comment 4b.
5 See e.g. S. RIALS, Les standards, notions critiques du droit, in Ch. PERELMAN (Ed.), Les notions à contenu variable en droit, Bruyland Brussels 1984, 39.
6 See e.g. R. DWORKIN, Law's Empire, Harvard Press 1986, 210-211.
7 H. BATIFFOL also stated "les principes de droit sont du droit", Problèmes de base de philosophie du droit, LGDJ Paris 1979, 262. See more specifically, T. BENDITT, Law as Rules and Principle, Harvester Press 1978. See eg. J. RAZ, Legal Prinicples and the Limits of Law, 81 Yale Law Journal 1972, 823.
8 Some principles such as Article 7.1 (good faith and fair dealing), Articles 3.8-3.20 (validity), Article 5.7(2) (price determination), Articles 7.4.13(2) (agreed payment for them non-performance) are more important than others "in the System of the principles" (Article 1.6,3).
9 R. DWORKIN has distinguished social relations governed by the "rulebook" from those guided by "principles". In the "rulebook model" the parties strictly adhere to established rules without questioning them; in the "model of principle", there is a continous debate about the validty and scope of the Principles, (R. DWORKIN, Law's Empire, Harvard Press 1986, 210-211). Moreover see M. BAYLES, Principles of Law, A Normative Analysis, Reidel Publishing Dordrecht 1987, 11.
10 See Ch. PERELMAN (Ed.), Les notions à contenu variable en droit, Bruyland Brussels 1984.
11 O. LANDO, The lex mereatoria in International Commercial Arbitration, 34 I.C.L.Q., 1985, 747, 751.
12 Except where the application of such usage would be unreasonable.
13 Under Article 4.3 "usage" and "the meaning commonly given to terms and expressions in the trade concerned" are two different standards for interpretation whereby "usages" would apply only when they are widely known and regularly observed in the particular trade while the "meaning commonly given in the trade concerned" could be relevant "even if it is peculiar to a trade sector to which only one, or even neither party belongs, provided that the expression or term concerned is one which is typical in that trade sector". In fact usages of a specific trade sector remain relevant even in spite of the fact that one or both parties ignored them.
14 These local usages, however should only be taken into account if they are applied in an indiscriminatory way to both domestic and foreign parties. (Article 1.8, Comment 4).
15 References in the UNIDROIT Principles to mere "good faith" and "fair dealing" have to be understood as references to "good faith and fair dealing in international trade" (Article 1.7, Comment 2). Such references are made in Article 3.5 (Relevant Mistake), Article 3.8 (Fraud), Article 4.8 (Supplying an omitted term), Article 5.2 (Implied Obligations).
16 Article 1.7, Comment 2.
17 E.g. Article 2.7 (Time of acceptance), Article 2.12 (Writings in confirmation), Article 2.14 (Contract with terms deliberately left open), Article 2.20 (Surprising Terms), Article 3.5 (Relevant mistake), Article 3.9 (Threat), Article 3.15 (Time limits), Article 3.16 (Partial avoidance), Article 4.1 (Intention of the parties), Article 5.4 (Duty of best efforts), Article 5.6 (Determination of quality of performance), Article 5.7 (Price determination), Article 5.8 (Contract for an indefinite period), Article 6.1.1 (Time of performance), Article 7.1.6 (Exemption clause), Article 7.1.7 (Force majeure), Article 7.2.2 (Performance of non-monetary obligation), Article 7.3.2 (Notice of termination), Article 7.4.5 (Proof of harm in case of replacement transaction), Article 7.4.6 (Proof of harm by current price).
18 See N. McCORMICK, On Reasonableness, in Ch. PERELMAN (Ed)., Les notions à contenu variable en droit, Bruyland Brussels 1984, 132.
19 Article 79 of the Vienna Convention, which deals with "force majeure" excludes "economic hardship". Also, as Article 78 addresses general difficulties of performance, recourse to domestic law to deal with these difficulties is equally barred (Article 7 (1)).
20 See H. VAN HOUTTE, Changed circumstances and pacta sunt servanda, in E. Gaillard (Ed.), Transnational rules in international commercial arbitration, ICC Publishing 1993, 105, 108-109 .
22 Article 6.2.2., Comment 2.
23 See ad hoc award June 30, 1992, unpublished, on the 15% rise of the price of spare parts and labour costs, cited in H. VAN HOUTTE, Article cit., note 44.
24 E.g. ICC award no. 6281, (1989), Yb. Comm. Arb. 1990, 96 .
25 E.g. Arbitral Tribunal Hamburg May 2, 1977, Yb. Comm. Arb., 1979, 202.
26 See e.g. Chamber of National and International Arbitration Milan, July 20, 1992, Yb. Comm. Arb., 1993, 80.
27 ICC award no. 2404 (1975) , J.D.I., 1976, 995.
28 ICC award no. 6281 (1989), Yb. Comm. Arb., 1990, 96 at 98.
29 ICC award no. 1512 (1971), Yb. Comm. Arb., 1976, 128 et 129 .
30 See ICC award no. 2216 (1974) , J.D.I., 1975, 917; ICC award no. 2478 (1974) , J.D.I. 1975, 925.
31 Arbitral Tribunal Hamburg award May 2, 1977, Yb. Comm. Arb., 1979, 202.
32 ICC award no. 6281 (1989), Yb. Comm. Arb., 1990, 96 at 98.Alsing Trading Co. and Swedish Match Co. v. Greece, I.C.L.O. 1959, 320.
33 Alsing Trading Co. and Swedish Match Co. v. Greece, I.C.L.Q. 1959, 320.
34 See e.g. W. MELIS, Force Majeure and Hardship Clauses in International Commercial Contracts in view of the Practice of the ICC Court of Arbitration, 1.J. Int. Arb., (1984), 213 .
35 For instance, ICC no. 2708 (1976) , J.D.L, 1977, 943.
36 ICC award no. 1512 (1971), J.D.I., 1974, 905 at 907; also ICC award no. 2404 (1975), J.D.I., 1976, 995.
37 ICC award no. 1512 (1971), Yb. Comm. Arb., 1976, 128 at 129.
38 See e.g. ICC award no. 3267 (1984), Yb. Comm. Arb., 1976, 128 at 129.
39 See S.E.E.E. v. Yugoslavia, J.D.I., 1959, 1075 at 1080; moreover, Ph. FOUCHARD, L'arbitrage commercial international, Dalloz Paris, 1965, 428 ; E. LOQUIN, "L'application des règles nationales dans l'arbitrage commercial international", in L'apport de la jurisprudence arbitrale, ICC Paris 1986, 87 at 99.
40 ICC award no. 2291 (1975) , J.D.I., 1976, 989; also ICC award no. 1512 (1971), J.D.I., 1974, 905.
41 Arbitraton Court of the Japan Shipping Exchange, award September 20, 1975, Yb.Comm. Arb., 1983, 153 at 155.
42 ICC award no. 3267 (1984), Yb. Comm. Arb., 1987, 87 at 109.
43 In S.E.E.E. v. Yugoslavia, the arbitrators stated e.g.: "Il sera contraire à la bonne foi que le gouvernement d'un Etat qui a commandé et reçu des prestations refusât d'en payer de vraie valeur et entendît tirer un profit de la dévaluation considérable de la monnaie de paiement" J.D.I., 1959, 1075 at 1080). See also Alsin award, where rebus sic stantibus would only have been considered when the preservation of the contract should involve the debtor's ruin, the creditor's correlative enrichment or at least a misuse of law akin to usery from the creditor's side (I.C.L.Q., 1959, 320).
44 See ad hoc award July 6, 1983, Yb. Comm. Arb., 1984, 69 at 70 : "The meaning of the rebussicstantibus clause cannot possibly be to let only one contracting party feel the consequences of the changed circumstances".
45 E McKENDRICK, Force Majeure and Frustration of Contracts, Lloyds London 1991, 38. Except in public work contracts, subject to the "Cahier Général des charges des marchés publics de travaux, de fournitures et de services" (Article 16 para 2).
46 Except in public work contracts, subject to the "Cahier Général des charges des marchés publics de travaux, de fournitures et de services" (Article 16 para 2).
47 See e.g. KÖBLER, Die "Clausula rebus sic stantibus" als allgemeiner Rechtsgrundsatz, JCB Mohr Tübingen 1991, 273 .
48 New Civil Code, Article
49 J. SAWADA, Subsequent conduct and supervening events. Tokyo 1968, 136.
50 Chamber of National and International Arbitration Milan, July 20, 1992, Yb. Comm. Arb., 1993, 80, 87.
51 Article 2.11, Comments no. 2.
52 See CISG Article 19 on the fact that the inclusion of an arbitration-clause in an acceptance, makes the latter a counter-offer. Under CISG Article 9, however, parties are bound by the usages of their trade.
53 See the Dutch and Swiss arbitration law as well as the German proposals: K. BERGER, International Commercial Arbitration, Kluwer Deventer 1993, 142-146 .
55 See i.a. K. BERGER, op .cit., 621-632; M. HUNTER and V. TRIEBEL, Awarding Interest in International Arbitration, J. Int. Arb. 1989, 7 ; P. KARRER, Transnational Law of Interest in international arbitration, in E. GAILLARD (Ed.), Transnational Rules in International Commercial Arbitration, ICC Publishing 1993, 223 .

Referring Principles
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