1. A contract shall be governed by the law chosen by the parties. The choice shall be made expressly or clearly demonstrated by the terms of the contract or the circumstances of the case. By their choice the parties can select the law applicable to the whole or to part only of the contract.

2. The parties may at any time agree to subject the contract to a law other than that which previously governed it, whether as a result of an earlier choice made under this Article or of other provisions of this Regulation. Any change in the law to be applied that is made after the conclusion of the contract shall not prejudice its formal validity under Article 11 or adversely affect the rights of third parties.

3. Where all other elements relevant to the situation at the time of the choice are located in a country other than the country whose law has been chosen, the choice of the parties shall not prejudice the application of provisions of the law of that other country which cannot be derogated from by agreement.

4. Where all other elements relevant to the situation at the time of the choice are located in one or more Member States, the parties' choice of applicable law other than that of a Member State shall not prejudice the application of provisions of Community law, where appropriate as implemented in the Member State of the forum, which cannot be derogated from by agreement.