No. I.1.2 - Prohibition of inconsistent behaviour 

(a) A party cannot set itself in contradiction to its previous conduct vis-à-vis another party if that latter party has acted in reasonable reliance on such conduct ("venire contra factum proprium"; "l'interdiction de se contredire au détriment d'autrui").

(b) Violation of this Principle may result in the loss, suspension, or modification of rights otherwise available to the party violating this Principle or in the creation of rights otherwise not available to the aggrieved party. 

1 This Principle follows from the general Principle of good faith and fair dealing. The other party's reliance may be based on a specific act, a statement or on the silence of the party. The conduct must be related to the contractual relationship existing between the parties.

2 Irrespective of the basis for the other party's reliance, the application of the Principle is limited by the standard of reasonableness. The other party must have acted in reasonable reliance on the first party's previous behavior. This means that it must have had justified reasons to base its reliance on the first party's conduct. Whether this is the case, must be determined against the circumstances of each individual case.

Please cite as: "Commentary to Trans-Lex Principle ,"
Arbitral Awards
Ad Hoc-Award of November 18, 1983 Benteler v. Belgium, J.Int'l Arb. 1984, at 184 et seq.
Arbitration CAS 2002/O/410 The Gibraltar Football Association (GFA)/Union des Associations Européennes de Football (UEFA)
Framatome-Award, YCA 1983, at 94, 101 et seq.
ICC Award No. 12456, Collection of ICC Arbitral Awards 2008-2011, at 811 et seq.
ICC Award No. 2520, Clunet 1976, at 992 et seq.
ICC Award No. 5832, Clunet 1988, at 1198 et seq.
ICC Award No. 6294, Clunet 1991, at 1050 et seq.
ICC Award No. 6363, YCA 1992, at 186 et seq.
ICC Interim Award to Case No. 10671, Clunet 2006, 1417
ICC Second Preliminary Award Made In Case No. 1512, YCA 1980, 170, 174 et seq. (also published in: ASA Bull. 1992, at 505 et seq.).
ICSID Award, AMCO Asia Corp. et al. v. The Republic of Indonesia et al., YCA 1985, at 61 et seq.
Iran-US Claims Tribunal, Abrahim Rahman Golshani v. The Government of The Islamic Republic of Iran, YCA 1994, at 421 et seq.
Iran-US Claims Tribunal, DIC of Delaware et al. v. Tehran Redevelopment Corp., YCA 1986, at 332 et seq.
Iran-US Claims Tribunal, Woodward-Clyde Consultants v. Iran et al., 3 IRAN-U.S. C.T.R., at 239 et seq.
Joseph Charles Lemire vs. Ukraine, ICSID Case No. ARB/06/18
Court Decisions
American Bank and Trust Company v Trinity Universal Insurance Company et al., 205 So.2d 35
ICJ North Sea Continental Shelf Cases, Separate Opinion of Judge Fouad Ammoun, ICJ Rep. 1969, at 1, 100 et seq.
Mitchell v McIntee, 514 P.2d 1357
Black, Henry Campell, Black's Law Dictionary, 6th ed., St. Paul 1990
Blessing, Marc, Das neue internationale Schiedsgerichtsrecht der Schweiz - Ein Fortschritt oder ein Rückschritt?, in: Böckstiegel (ed.), Die internationale Schiedsgerichtsbarkeit in der Schweiz (II), Cologne, Berlin, Bonn, Munich 1989, at 13 et seq.
Bowden, Paul, L‘interdiction des se contredire au détriment d‘autrui (estoppel) as a Substantive Transnational Rule in International Commercial Arbitration, in: Gaillard (ed.); Transnational Rules in Commercial Arbitration (ICC Publ. Nr. 480,4), Paris 199, at 125 et seq.
Brunetti, Maurizio, The Lex Mercatoria in Practice: The Experience of the Iran- United States Claims Tribunal, in: (2002) 18 Arb. Int., 355 et seq.
Cheng, Bin, General Principles Of Law as Applied by International Courts and Tribunals, reprinted, Cambridge 1987
Craig, W. Laurence/ Park, William W./ Paulsson, Jan, International Chamber of Commerce Arbitration, 3rd ed., Dobbs Ferry 2000
Dasser, Felix, Internationale Schiedsgerichte und Lex Mercatoria, Zürich 1989
Dölle, Hans (ed.), Kommentar zum Einheitlichen Kaufrecht, Comment on Art. 10 by Ulrich Huber and on Art. 17 by Eduard Wahl, Munich 1976.
Dickstein, Michael E., Revitalizing the International Law Governing Concession Agreements, 5/6 Int’l Tax & Bus.Lawy. 1987/88, at 54 et seq.
Domingo, Ortega, Rodriguez-Antolin, Zambrana, Principios de Derecho Global, Navarra, 2006
Esser, Josef, Grundsatz und Norm in der richterlichen Fortbildung des Privatrechts, 4th ed., Tübingen 1990
Ferrari, Franco, Das Verhältnis zwischen den Unidroit-Grundsätzen und den allgemeinen Grundsätzen internationaler Einheitsprivatrechtskonventionen, JZ 1998, at 9 et seq.
Ferrari, Franco, The CISG's Interpretative Goals, Its Interpretative Method and Its General Principles in Case Law (Part II), IHR 5/2013, at 181 et seq.
Fouchard Gaillard Goldman on International Commercial Arbitration (edited by Emmanuel Gaillard and John Savage) The Hague 1999
Gaillard, Emmanuel, L'Interdiction de se Contredire au Détriment d'Autrui comme Principe Général du Droit du Commerce International, Rev.d.Arb. 1985, at 241 et seq.
Herber, Rolf/ Czerwenka, Beate, Internationales Kaufrecht, Munich 1991
Kersley, R.H., M.A., LL.M./ Broom, Herbert, LL.D., A Selection of Legal Maxims, 10th ed. London, 1939
Knütel, Rolf, Rechtseinheit in Europa und römisches Recht, 3 ZEuP 1994, at 244 et seq.
Lalive, Pierre, Ordre Public Transnational (ou Réellement International) Et Arbitrage International. Rev.d.Arb. 1986, at 329 et seq.
Lalive, Pierre, The First World Bank Arbitration (Holiday Inns v. Morocco) - Some Legal Problems, 51 Brit.Yb.Int’l L. 1980, at 123 et seq.
Lando, Ole / Beale, Hugh (eds.), Comment to Art. 1:201 PECL, p. 114 et seq.
Langen, Eugen, Transnationales Recht, Heidelberg 1981.
Lauterpacht, Hersch, Private Law Sources and Analogies of International Law, New York, Toronto 1927
Loquin, La réalité des usages du commerce international, RIDéco 1989, at 163 et seq.
Mayer, Pierre, Le Principe de Bonne Foi devant les Arbitres du Commerce International, in: Festschrift Pierre Lalive, Basel, Frankfurt a.M. 1993, at 543 et seq.
Müller, Georg, Vorvertragliche und vertragliche Informationspflichten nach englischem und deutschem Recht, Heidelberg 1994
Neumann, Thomas, The Duty to Cooperate in International Sales - The Scope and Role of Article 80 CISG (2012), p. 110 et seq.
Paulsson, Jan, La Lex Mercatoria dans l‘Arbitrage C.C.I, Rev.d.Arb. 1990. at 55 et seq.
Romero, Eduardo Silva, Note to ICC Award No. 10671, Clunet 2006, at 1423 et seq.
Schlechtriem, Peter (ed.), English Commentary on the UN Convention on the International Sale of Goods (CISG), Comment on Art. 7 by Rolf Herber, Oxford 1998
Schmitthoff, Clive, International Trade Usages, Institute of International Business Law And Practice Newsletter, Special Issue, ICC Publ.440,4, Paris 1987
Staehelin, Estoppel und Vertrauensprinzip, in: Festschrift Simonius, Basel 1955, at 381 et seq.
Verdross, Alfred/ Simma, Bruno, Universelles Völkerrecht, 3rd ed., Berlin 1984
Wühler, Norbert, Application of General Principles of Law, in van den Berg (ed.), Planning efficient Arbitration Proceedings - The Law Applicable in International Arbitration, p. 553 et seq.
International Legislation
United Nations Convention on Contracts for the International Sale of Goods (CISG)
Principles / Restatements
UNIDROIT Principles of International Commercial Contracts
Contract Clauses
Consistent Behavior
Lease Contract
Responsibilities of both parties
Party B shall not do anything harmful or damaging to the good standing and reputation of Party A.
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