Artikel 18

1. Where a decision is made in a Contracting State where the creditor is habitually resident, proceedings to modify the decision or to make a new decision cannot be brought by the debtor in any other Contracting State as long as the creditor remains habitually resident in the State where the decision was made.
2. Paragraph 1 shall not apply –
a) where, except in disputes relating to maintenance obligations in respect of children, there is agreement in writing between the parties to the jurisdiction of that other Contracting State;
b) where the creditor submits to the jurisdiction of that other Contracting State either expressly or by defending on the merits of the case without objecting to the jurisdiction at the first available opportunity;
c) where the competent authority in the State of origin cannot, or refuses to, exercise jurisdiction to modify the decision or make a new decision; or
d) where the decision made in the State of origin cannot be recognised or declared enforceable in the Contracting State where proceedings to modify the decision or make a new decision are contemplated.