IS the mass collection of communications metadata legally equivalent to surveillance of the content of those communications? If so, does EU fundamental rights law have any bearing on its application? If it does, what is the appropriate relationship between the Court of Justice of the European Union and Member States’ courts in balancing in the competing interests at stake? These questions came before a Grand Chamber of the CJEU in Joined Cases C-203/15 and C-698/15, Tele2 Sverige AB v Post- och telestyrelsen and Secretary of State for the Home Department v Tom Watson and Others ECLI:EU:C:2016:970 (Watson).