The Civil Jurisdiction and Judgments Act 1982 (Amendment) Order 1989

Article 17

If the parties, one or more of whom is domiciled in a Contracting State, have agreed that a court or the courts of a Contracting State are to have jurisdiction to settle any disputes which have arisen or which may arise in connection with a particular legal relationship, that court or those courts shall have exclusive jurisdiction. Such an agreement conferring jurisdiction shall be either in writing or evidenced in writing or, in international trade or commerce, in a form which accords with practices in that trade or commerce of which the parties are or ought to have been aware. Where such an agreement is concluded by parties, none of whom is domiciled in a Contracting State, the courts of other Contracting States shall have no jurisdiction over their disputes unless the court or courts chosen have declined jurisdiction.