Case C-319/06: Judgment of the Court (First Chamber) of 19 June 2008 — Commission of the European Communities v Grand Duchy of Luxembourg (Failure of a Member State to fulfil obligations — Posting of workers — Freedom to provide services — Directive 96/71/EC — Public policy provisions — Weekly rest days — Obligation to produce documents relating to a posting on demand by the national authorities — Obligation to designate an ad hoc agent residing in Luxembourg to retain all the documents necessary for monitoring purposes)