Judgment in Joined Cases C-203/15 Tele2 Sverige AB v Post-och telestyrelsen and C-698/15 Secretary of State for the Home Department v Tom Watson and Others
The Members States may not impose a general obligation to retain data on providers of electronic communications services. EU law precludes a general and indiscriminate retention of traffic data and location data, but it is open to Members States to make provision, as a preventive measure, for targeted retention of that data solely for the purpose of fighting serious crime, provided that such retention is, with respect to the categories of data to be retained, the means of communication affected, the persons concerned and the chosen duration of retention, limited to what is strictly necessary.
Access of the national authorities to the retained data must be subject to conditions, including prior review by an independent authority and the data being retained within the EU. (See the ECJ press statement for more details: http://curia.europa.eu/jcms/upload/docs/application/pdf/2016-12/cp160145en.pdf)
