A/HRC/27/37 own constitute an interference with privacy. From the perspective of the right to privacy, this distinction is not persuasive. The aggregation of information commonly referred to as “metadata” may give an insight into an individual’s behaviour, social relationships, private preferences and identity that go beyond even that conveyed by accessing the content of a private communication. As the European Union Court of Justice recently observed, communications metadata “taken as a whole may allow very precise conclusions to be drawn concerning the private lives of the persons whose data has been retained.”5 Recognition of this evolution has prompted initiatives to reform existing policies and practices to ensure stronger protection of privacy. 20. It follows that any capture of communications data is potentially an interference with privacy and, further, that the collection and retention of communications data amounts to an interference with privacy whether or not those data are subsequently consulted or used. Even the mere possibility of communications information being captured creates an interference with privacy,6 with a potential chilling effect on rights, including those to free expression and association. The very existence of a mass surveillance programme thus creates an interference with privacy. The onus would be on the State to demonstrate that such interference is neither arbitrary nor unlawful. 2. What is “arbitrary” or “unlawful”? 21. Interference with an individual’s right to privacy is only permissible under international human rights law if it is neither arbitrary nor unlawful. In its general comment No. 16, the Human Rights Committee explained that the term “unlawful” implied that no interference could take place “except in cases envisaged by the law. Interference authorized by States can only take place on the basis of law, which itself must comply with the provisions, aims and objectives of the Covenant”.7 In other words, interference that is permissible under national law may nonetheless be “unlawful” if that national law is in conflict with the provisions of the International Covenant on Civil and Political Rights. The expression “arbitrary interference” can also extend to interference provided for under the law. The introduction of this concept, the Committee explained, “is intended to guarantee that even interference provided for by law should be in accordance with the provisions, aims and objectives of the Covenant and should be, in any event, reasonable in the particular circumstances”.8 The Committee interpreted the concept of reasonableness to indicate that “any interference with privacy must be proportional to the end sought and be necessary in the circumstances of any given case”.9 22. Unlike certain other provisions of the Covenant, article 17 does not include an explicit limitations clause. Guidance on the meaning of the qualifying words “arbitrary or unlawful” nonetheless can be drawn from the Siracusa Principles on the Limitation and Derogation Provisions in the International Covenant on Civil and Political Rights;10 the practice of the Human Rights Committee as reflected in its general comments, including 5 6 7 8 9 10 Court of Justice of the European Union, Judgment in Joined Cases C-293/12 and C-594/12, Digital Rights Ireland and Seitlinger and Others, Judgment of 8 April 2014, paras. 26-27, and 37. See also Executive Office of the President, “Big Data and Privacy: A Technological Perspective” (available from www.whitehouse.gov/sites/default/files/microsites/ostp/PCAST/pcast_big_data_and_privacy__may_2014.pdf), p. 19. See European Court of Human Rights, Weber and Saravia v. Germany, para. 78; Malone v. UK, para. 64. Official Records of the General Assembly (see footnote 3), para. 3. Ibid., para. 4. Communication No. 488/1992, Toonan v. Australia, para. 8.3; see also communications Nos. 903/1999, para 7.3, and 1482/2006, paras. 10.1 and 10.2. See E/CN.4/1985/4, annex. 7