Request for a preliminary ruling under Article 267 TFEU from the Cour constitutionnelle (Belgium), made by decision of 6 April 2011. Judgment of the Court (First Chamber) dated 8 May 2013: 1. Treaty rules governing freedom of movement for persons and the measures adopted to implement them cannot be applied to activities which have no factor linking them with any of the situations governed by EU law and which are confined in all relevant respects within a single Member St