This was superseded by the Investigatory Powers Act 2016, a comprehensive statute which made public a number of previously secret powers (equipment interference, bulk retention of metadata, intelligence agency use of bulk personal datasets), and enables the Government to require internet service providers and mobile phone companies to maintain records of (but not the content of) customers' Internet connections for 12 months. In addition, it created new safeguards, including a requirement for judges to approve the warrants authorised by a Secretary of State before they come into force. The Act was informed by two reports by David Anderson QC, the UK's Independent Reviewer of Terrorism Legislation: A Question of Trust (2015) and the report of his Bulk Powers Review (2016), which contains a detailed appraisal (with 60 case studies) of the operational case for the powers often characterised as mass surveillance. It may yet require amendment as a consequence of legal cases brought before the Court of Justice of the European Union and the European Court of Human Rights.