Special rule on defence
The “debtor may contest a claim from the creditor on the ground that there is no such obligation under both the law of the State of the habitual residence of the debtor and the law of the State of the common nationality (For the replacement of the concept of ‘nationality’ by that of ‘domicile’ (Article 9), see Jurisdiction - General provisions, Article 3) of the parties” (Article 6). This rule may, however, only be used with regard to cases “of maintenance obligations other than those arising from a parent-child relationship towards a child and those referred to in Article 5”.