Elektrobudowa v Sähköliitto

Reference for a preliminary ruling — Articles 56 TFEU and 57 TFEU — Directive 96/71/EC —Articles 3, 5 and 6 — Workers of a company with its seat in Member State A, posted to carry out works in Member State B — Minimum wage provided for by the collective agreements of Member State B —Locus standi of a trade union with its seat in Member State B — Legislation of Member State A prohibiting the assignment to a third party of claims relating to pay