MODIFICATION OF CLAUSES ON THE BASIS OF THE CONTRACTUAL CONDUCT OF THE PARTIES. APPLICATION OF ESTOPPEL DOCTRINE Lecturer Bazil OGLINDĂ 1 Abstract Within the context of identifying a modern trend for increasing the flexibility of contract law, trend which is also internalized by the Romanian legal system through the adoption of the Civil Code from 2009, we intend to analyse the implications as regards the modification of contracts. Specifically, we intend to answer to the following question: May a clause which requires modification in a certain form only (conventional formalism) be annihilated by the parties’ conduct throughout the performance of the contract (namely, a conduct whereby they ignore such clause)? In order to answer to this question, we consider that it is useful to present the mechanism pursuant to which foreign legal systems or the great European projects for the unification of contract law 2 settled this issue, following that, at the end, we analyse the viability of importing such mechanisms into the Romanian contract law and the legal ground pursuant to which these mechanisms may operate in the context of the new Romanian Civil Code. Keywords: modification in a certain form only, the parties’ conduct throughout the performance of the contract, estoppel, new Romanian Civil Code. JEL Classification: K12, K33 1. Preliminary remarks A. What is estoppel? The origin of the concept. Estoppel represents a legal concept of Anglo-Saxon origin which is also integrated by the continental law (e.g. French law), which, in recent years, makes its way in international commercial arbitration; where it is regarded as pertaining to “lex mercatoria”, being an equitable rule of law, compliant with all national legal orders. 3 B. „Types of Estoppel” Estoppel, having as basis a contradictory behaviour of one of the parties, is of three types: 4 1 Bazil Oglindă – Bucharest University of Economic Studies, Law Department, office@onvlaw.ro 2 During the last 15 years, efforts have been made and are still made in order to accomplish certain legislative projects at Community level aimed at codifying the Contract Law within European Union’s countries (M. Fabre-Magnan, Les obligations, Presses Universitaires de France, Paris, 2004, p. 117-121; L. Pop, Treaty of Civil Law. Obligations, Vol. II, Universul Juridic Publishing House, Bucharest, p. 32.) Thus, the Principles for International Commercial Contracts were published for the first time in 1994 under UNIDROIT’s aegis. In 2004, a new edition of UNIDROIT Principles was published. As regards the purpose of UNIDROIT Principles, in the preamble it is provided that “These Principles set forth general rules for international commercial contracts. They shall be applied when the parties have agreed that their contract will be governed by them. They may be applied when the parties have agreed that their contract be governed by the general principles of law, the “lex mercatoria” or the like. They may be a pplied 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 model for national and international legislators.” (International Institute for the Unification of the Private Law is an independent intergovernmental organisation, having its headquarters in Rome, Italy. For the analysis of UNIDROIT Principles, please see V. Pătulea, Gh. Stancu, Structural Change of the Framework for the Regulation of the Contractual Obligational Legal Relations (I) in “Dreptul” Journal, No. 1/2008, p. 20-24). 3 Osborn‘s Concise Law Dictionary, Thomson – Sweet & Maxwell, London, 2005, p. 165. 4 Specialised literature, following the analysis of the jurisprudence of the states that recognise the concept, identified the following types of estoppel: - estoppel by conduct (estoppel by representation, estoppel in pais) – it opposes to the party that intends to deny the consequences resulted from its prior behaviour, from a personal fact; it precludes the party to contradict its own representation of the reality, which was previously adopted, in particular if such representation induced to the adversary a correlative belief, who would be prejudiced, if such belief is challenged. This mean is, by assumption, defensive, because it represents an obstacle against any claim (for annulment, for restitution, etc.) which aims at re-discussing a situation that was perceived by the defendant, in consideration of the behaviour of the claimant, as acquired, earned; - estoppel by deed – it is invoked against the party that intends to deny what it stated in a deed, official document or public registry;