A court in the Member State where the defendant is domiciled, seised under Article 4(1) of an infringement action concerning a patent granted in another Member State, still has jurisdiction to hear that action even if the defendant raises the patent's validity as a defence. Only the courts of that other Member State have exclusive jurisdiction to rule on validity.

Article 24(4) does not apply to courts of third States and gives them no jurisdiction, exclusive or otherwise, to assess the validity of patents granted or validated by those States. A Member State court seised under Article 4(1) of an infringement action concerning a patent granted or validated in a third State has jurisdiction under Article 4(1) to rule on a validity defence - provided that its decision does not affect the existence or content of that patent in the third State or cause that State's national register to be amended.

Article 4(1) and Article 25 of Regulation No 1215/2012 preclude legislation of a Member State which, in disputes about credit agreements with international elements falling within that regulation, lets debtors sue non-authorised lenders either in the courts of the State where the lenders have their registered office or in the courts of the place where the debtors have their domicile or head office, but allows creditors to sue debtors only in the courts of the State where those debtors are domiciled - whether the debtors are consumers or professionals.