1. Article 18 of the Convention of 27 September 1968 on Jurisdiction and the Enforcement of Judgments in Civil and Commercial Matters applies even where the parties have by agreement designated a court which is to have jurisdiction within the meaning of Article 17 of that Convention.

2. Article 18 of the Convention of 27 September 1968 must be interpreted as meaning that the rule on jurisdiction which that provision lays down does not apply where the defendant not only contests the court's jurisdiction but also makes submissions on the substance of the action, provided that, if the challenge to jurisdiction is not preliminary to any defence as to the substance, it does not occur after the making of the submissions which under national procedural law are considered to be the first defence addressed to the court seised.

3. Article 22 of the Convention of 27 September 1968 applies only where related actions are brought before courts of two or more Contracting States.

4. Article 17 of the Convention of 27 September 1968 must be interpreted as meaning that the legislation of a Contracting State may not allow the validity of an agreement conferring jurisdiction to be called in question solely on the ground that the language used is not that prescribed by that legislation.