[2] SHARMA, K.M. From Sanctity to Fairness: An Uneasy Transition in the Law of Contracts? NewYork Law School Journal of International & Comparative Law, vol. 18, 1997, p. 95.

[3] Not only that is the basis of contract law in Civil Law countries, but it is also the cornerstone of international treaties. See PARRY, Clive. Derecho de Los Tratados in: SORENSEN, MAX (ed). Manual de Derecho Internacional Público. Mexico: Fondo de Cultura Economica, 2000, p. 200; see also KELSEN, Hans. El Contrato y El Tratado. Mexico: Colofón, 1994, p.p. 3,4 & 5.

[4] Black's Law Dictionary defines rebus sic stantibus as follows: "The principle that all agreements are concluded with the implied condition that they are binding only as long as there are no major changes in the circumstances." See BLACK, Henry Campbell. Law Dictionary. 7th ed. St. Paul, Minn.: West Group, 1999.

[5] LITVINOFF, Saul. Force majeure, Failure of Cause and Theorie de l’Imprevision: Lousiana Law and Beyond. Lousiana Law Review, vol. 46, 1985, p.15

[6] PLANIOL, Marcel. Treatise on the Civil Law. 11 ed. Baton Rouge: Lousiana State Law Institute, 1959, 1168A.

[7] DAVID, Rene. Frustration of Contract in French Law. Journal of Comparative Legislation, vol. 28,1946, p.p.13-14.

[8] ROSENN, Keith. Law and Inflation. Philadelphia: University of Pennsylvania Press, 1982, p. 87.

[9] Art. 242 of the German Civil Code provides that a debtor is obligated to render performance as required by good faith, taking account of common usage. Cited in HAY, Peter. Frustration and its Solution in German Law. American Journal of Comparative Law, 1961, p.p. 345-356.

[10]COHN, J. Frustration of Contract in German Law. Journal of Comparative Legislation and International Law, v. 28, 1946, p.p. 20-21.

[11]SCHWENZER, Ingeborg. Introduction to German Law. In: EBKE, Werner F. and FINK, Matthew. The Law of Contracts. The Hague: Klumer Law International, 1996.

[12]ROSENN, Keith. Law and Inflation. Philadelphia: University of Pennsylvania Press, 1982, p. 87.

[13]Here is the original and entire version of art. 1467 of the Italian Civil Code: "Nei contratti a esecuzione continuata o periodica ovvero a esecuzione differita, se la prestazione di una delle parti è divenuta eccessivamente onerosa per il verificarsi di avvenimenti straordinari e imprevedibili, la parte che deve tale prestazione può domandare la risoluzione del contratto, con gli effetti stabiliti dall'art. 1458 (att. 168). La risoluzione non può essere domandata se la sopravvenuta onerosità rientra nell'alea normale del contratto. La parte contro la quale è domandata la risoluzione può evitarla offrendo di modificare equamente le condizioni del contratto (962, 1623, 1664, 1923)."

[14]Art. 1458 determines that "Dissolution of a contract for non-performance has retroactive effect as between the parties, except in the case of contracts for continuous or periodic performance, with respect to which the effect of dissolution does not extend to performance already made. Dissolution, even if expressly agreed upon (1456), does not prejudice rights acquired by third persons, except for the effects of transcription (2652 no. 1) of the action for dissolution.

[15] VEYTIA, Hernani. The Requirement of Justice and Equity in Contracts. Tulane Law Review, vol. 69, p. 1191.

[16]This is the original and entire art. 1198 of the Argentine Civil code: "Los contratos deben celebrarse, interpretarse y ejecutarse de buena fe y de acuerdo con lo que verosímilmente las partes entendieron o pudieron entender, obrando con cuidado y previsión. En los contratos bilaterales conmutativos y en los unilaterales onerosos y conmutativos de ejecución diferida o continuada, si la prestación a c argo de una de las partes se tornara excesivamente onerosa, por acontecimientos extraordinarios e imprevisibles, la parte perjudicada podrá demandar la resolución del contrato. El mismo principio se aplicará a los contratos aleatorios cuando la excesiva onerosidad se produzca por causas extrañas al riesgo propio del contrato. En los contratos de ejecución continuada la resolución no alcanzará a los efectos ya cumplidos. No procederá la resolución, si el perjudicado hubiese obrado con culpa o estuviese en mora. La otra parte podrá impedir la resolución ofreciendo mejorar equitativamente los efectos del contrato."

[17]Mercosur (or Mercosul) presently comprises four countries: Argentina, Brazil, Paraguay and Uruguay.

[18]Article 672 of Paraguay's Civil Code states: "En los contratos de ejecucíon diferida, si sobrevinieren circunstancias imprevisibles y extraordinarias que hicieren la prestación excessivamente onerosa, el deudor podrá pedir la resolución de los efectos del contracto pendientes de cumplimento. La resolución no procederá cuando la onerosidad sobrevenida estuviera dentro del álea normal del contrato, o si el deudor fuere culpable. El demandado podrá evitar la resolución del contrato ofreciendo su modificación equitativa. Si el contrato fuere unilateral, el deudor podrá demandar la reducción de la prestación o la modificación equitativa de manera de ejecutarlo."

[19]OLIVEIRA, Anísio José de. A Teoria da Imprevisão nos Contratos. São Paulo: LEUD, 1991.

[20]Decision rendered by Superior Tribunal de Justiça, in Resp. n. 177.018-MG.

[21]Published in Revista Superior Tribunal de Justiça, vol. 23, p. 329.

[22]Paradine v. Jane, Aleyn 26,27, 82 Eng. Rep. 897, 897 (K.B. 1647).

[23]6 Williston § 1931

[24]Williams v. Lloyd, W. Jones, 179, 82 Eng. Rep. 95 (K.B. 1629)

[25]FARNSWORTH, E. ALLAN. Contracts. New York: Little, Brown and Co., 1990.

[26]Taylor v. Caldwell, B & S. 826, 122 Eng. Rep. 309 (K.B. 1863).

[27]Printing and Numerical Registering Co. v. Sampson, 19 L.R. -Eq. 462, 465 (1875).

[28]Davis Contractors Ltd. v. Fareham U.D.C , A.C. 696 H.L. (1956)

[29]INTERNATIONAL ASSOCIATION OF LEGAL SCIENCE. International Encyclopedia of International Law: Breach of Contract. New York: Oceana, 1973.

[30]Perillo explains that "performance is rendered impracticable only with extreme and unreasonable difficulty". See PERILLO, Joseph. The Law of Contracts. 3rd Edition. St. Paul, Minn.: West, 1987.