"437 Abnormal change in circumstances 1. If the circumstances on which the parties based their decision to enter into a contract have undergone an abnormal change, the injured party is entitled to termination of the contract or to modify it in accordance with principles of equity if fulfilment of that party's obligations under the contract would be a serious breach of the principles of good faith and if the abnormal changes do not form part of the risks covered by the contract. 2. If termination is requested, the counterparty may oppose by stating that it accepts modification of the contract in accordance with the previous paragraph."
“Summarising the main points made above, because of the right to assign to a bank outside Portugal, the use of standard international documentation, the practical necessity for the relationship with a bank outside Portugal, the international nature of the swaps market in which the contracts were concluded, and the fact that back-to-back contracts were concluded with a bank outside Portugal in circumstances in which such hedging arrangements are routine, the court's conclusion is that Art. 3(3) of the Rome Convention is not engaged because all the elements relevant to the situation at the time of the choice were not connected with Portugal only. In short, these were not purely domestic contracts. Any other conclusion, the court believes, would undermine legal certainty.”
“It is sufficient to take a rule out of Art. 3(3) of the Rome Convention, in the court's judgment, if the rule can be disapplied by agreement between the parties whether ex ante or ex post. To take the present case, this distinguishes Art. 437 of the Civil Code, which deals with change of circumstances, from Art. 1245, which invalidates gaming and betting contracts. BST accepts that this is mandatory. Plainly, parties cannot contract out of rules applicable to gaming and betting contracts in any circumstances.”
“8. Article 3(3) provides that the choice of a foreign law by the parties, whether or not accompanied by the choice of a foreign tribunal, shall not, where all other elements relevant to the situation at the time of the choice are connected with one country only, prejudice the application of the law of that country which cannot be derogated from by contract, hereinafter called ‘mandatory rules’. This solution is the result of a compromise between two lines of argument which have been diligently pursued within the Group: the wish on the one hand of certain experts to limit the parties’ freedom of choice embodied in this Article by means of a correcting factor specifying that the choice of a foreign law would be insufficient per se to permit the application of that law if the situation at the moment of choice did not involve another foreign element, and on the other the concern of other experts, notably the United Kingdom experts, that such a correcting factor would be too great an obstacle to the freedom of the parties in situations in which their choice appeared justified, made in good faith, and capable of serving interests worthy of protection. In particular these experts emphasized that departures from the principle of the parties’ freedom of choice should be authorized only in exceptional circumstances such as the application of the mandatory rules of a law other than that chosen by the parties; they also gave several examples of cases in which the choice of a foreign law by the parties was fully justified although there was apparently no other foreign element in the situation. The Group recognized that this concern was well founded, while maintaining the principle that the choice by the parties of a foreign law where all the other elements relevant to the situation at the time of the choice are connected with one country only shall not prejudice the application of the mandatory rules of the law of that country.”
“49. Thus, to give full effect to the principle of the freedom of contract of the parties to a contract, which is the cornerstone of the Rome Convention, reiterated in the Rome I Regulation, it must be ensured that the choice freely made by the parties as regards the law applicable to their contractual relationship is respected in accordance with art 3(1) of the Rome Convention, so that the plea relating to the existence of a ‘mandatory rule’ within the meaning of the legislation of the member state concerned, as referred to in art 7(2) of that convention, must be interpreted strictly.”
“42. For the purposes of determining the precise scope of Article 9 of the Rome I Regulation, it should be noted that it is apparent from Article 3(1) thereof and, so far as concerns, more specifically, employment contracts, Article 8(1), that freedom of contract of the contracting parties as to the choice of the applicable law constitutes the general principle laid down by the Rome I Regulation. 43. Article 9 of the Rome I Regulation derogates from that principle that the applicable law is to be freely chosen by the parties to the contract. As recital 37 of the regulation states, this exception has the purpose of enabling the court of the forum to take account of considerations of public interest in exceptional circumstances. 44. As a derogating measure, Article 9 of the Rome I Regulation must be interpreted strictly (see, by analogy, judgment of17 October 2013 , Unamar, C-184/12, EU:C:2013:663, paragraph 49). … 46. Moreover, to permit the court of the forum to apply overriding mandatory provisions of the legal order of Member States other than those which are expressly referred to in Article 9(2) and (3) of the Rome I Regulation would be liable to jeopardise full achievement of the regulation’s general objective, which, as stated in recital 16, is legal certainty in the European area of justice.”