Artikel 1

1. A Contracting State which institutes or intervenes in proceedings before a court of another Contracting State submits, for the purpose of those proceedings, to the jurisdiction of the courts of that State.
2. Such a Contracting State cannot claim immunity from the jurisdiction of the courts of the other Contracting State in respect of any counterclaim:
(a) arising out of the legal relationship or the facts on which the principal claim is based;
(b) if, according to the provisions of this Convention, it would not have been entitled to invoke immunity in respect of that counterclaim had separate proceedings been brought against it in those courts.
3. A Contracting State which makes a counterclaim in proceedings before a court of another Contracting State submits to the jurisdiction of the courts of that State with respect not only to the counterclaim but also to the principal claim.