A passenger's compensation claim against an operating air carrier with which the passenger did not conclude a contract does not fall within Articles 15 to 17 on special jurisdiction over consumer contracts.

Article 16(1) does not apply where a consumer sues in the courts of the place where he is domiciled to assert not only his own claims, but also claims assigned by other consumers domiciled in the same Member State, in other Member States, or in non-member countries.

Article 15(1)(c) of Regulation No 44/2001, read in conjunction with Article 16(1), may - in so far as it concerns a contract concluded in the context of a commercial or professional activity directed by the professional to the Member State of the consumer's domicile - also apply to a contract between the same consumer and professional that, on its own, does not fall within that directed activity, provided that it is closely linked to a contract previously concluded by those same parties in the context of that activity. It is for the national court to determine whether that link exists, in particular whether the parties to both contracts are identical in law or in fact, whether both contracts have the same economic objective concerning the same specific subject-matter, and whether the second contract complements the first by making it possible for the first contract's economic objective to be achieved.

In circumstances such as those at issue in the main proceedings, the "other party to the contract" in Article 16(1) of Regulation No 44/2001 also includes the contracting partner of the operator with which the consumer concluded the contract, where that partner has its registered office in the Member State in which the consumer is domiciled.

Where a consumer under a long-term mortgage loan contract that requires each party to inform the other of any change of address renounces his domicile before proceedings are brought for breach of his contractual obligations, the courts of the Member State of the consumer's last known domicile have jurisdiction under Article 16(2) if they have been unable to determine the defendant's current domicile under Article 59 and have no firm evidence that the defendant is domiciled outside the European Union. Regulation No 44/2001 does not preclude a national procedural rule that, to avoid a denial of justice, allows proceedings to be brought against, and in the absence of, a person whose domicile is unknown - provided that, before ruling, the court seised is satisfied that all investigations required by the principles of diligence and good faith have been undertaken to trace the defendant.