opportunities for, the two spouses. Hence judges in the participating Member States should be aware of the importance of an informed choice on the part of the two spouses concerning the legal implications of the choice-of-law agreement concluded.
(19) Rules on material and formal validity should be defined so that the informed choice of the spouses is facilitated and that their consent is respected with a view to ensuring legal certainty as well as better access to justice. As far as formal validity is concerned, certain safeguards should be introduced to ensure that spouses are aware of the implications of their choice. The agreement on the choice of applicable law should at least be expressed in writing, dated and signed by both parties. However, if the law of the participating Member State in which the two spouses have their habitual residence at the time the agreement is concluded lays down additional formal rules, those rules should be complied with. For example, such additional formal rules may exist in a participating Member State where the agreement is inserted in a marriage contract. If, at the time the agreement is concluded, the spouses are habitually resident in different participating Member States which lay down different formal rules, compliance with the formal rules of one of these States would suffice. If, at the time the agreement is concluded, only one of the spouses is habitually resident in a participating Member State which lays down additional formal rules, these rules should be complied with.
(20) An agreement designating the applicable law should be able to be concluded and modified at the latest at the time the court is seized, and even during the course of the proceeding if the law of the forum so provides. In that event, it should be sufficient for such designation to be recorded in court in accordance with the law of the forum.
(21) Where no applicable law is chosen, and with a view to guaranteeing legal certainty and predictability and preventing a situation from arising in which one of the spouses applies for divorce before the other one does in order to ensure that the proceeding is governed by a given law which he considers more favourable to his own interests, this Regulation should introduce harmonised conflict-of-laws rules on the basis of a scale of successive connecting factors based on the existence of a close connection between the spouses and the law concerned. Such connecting factors should be chosen so as to ensure that proceedings relating to divorce or legal separation are governed by a law with which the spouses have a close connection.
(22) Where this Regulation refers to nationality as a connecting factor for the application of the law of a State, the question of how to deal with cases of multiple nationality should be left to national law, in full observance of the general principles of the European Union.
(23) If the court is seized in order to convert a legal separation into divorce, and where the parties have not made any choice as to the law applicable, the law which applied to the legal separation should also apply to the divorce. Such continuity would promote predictability for the parties and increase legal certainty. If the law applied to the legal separation does not provide for the conversion of legal separation into divorce, the divorce should be governed by the conflict-of-laws rules which apply in the absence of a choice by the parties. This should not prevent the spouses from seeking divorce on the basis of other rules in this Regulation.