Case C-306/12: Judgment of the Court (Second Chamber) of 10 October 2013 (request for a preliminary ruling from the Landgericht Saarbrücken — Germany) — Spedition Welter GmbH v Avanssur SA (Insurance against civil liability in respect of the use of motor vehicles and enforcement of the obligation to insure against such liability — Directive 2009/103/EC — Article 21(5) — Claims representative — Authority to accept service of judicial documents — National rule making the validity of that service conditional on the express grant of an authority to accept it — Interpretation in conformity with Union law)