A/HRC/13/37 that have ratified the First Optional Protocol to the Covenant, the procedure for individual complaints. 16. The wording of article 17 of the Covenant prohibits “arbitrary or unlawful” interference with privacy, family or correspondence, as well as “unlawful attacks” on a person’s honour and reputation. This can be contrasted with the formulation of such provisions as article 12, paragraph 3; article 18, paragraph 3; article 19, paragraph 3; article 21 and article 22, paragraph 2, which all spell out the elements of a test for permissible limitations. In its most elaborate form, this test is expressed in article 21 and article 22, paragraph 3, as consisting of the following three elements: (a) restrictions must be prescribed by national law; (b) they must be necessary in a democratic society; and (c) they must serve one of the legitimate aims enumerated in each of the provisions that contain a limitations clause. 17. The Special Rapporteur takes the view that, despite the differences in wording, article 17 of the Covenant should also be interpreted as containing the said elements of a permissible limitations test. Restrictions that are not prescribed by law are “unlawful” in the meaning of article 17, and restrictions that fall short of being necessary or do not serve a legitimate aim constitute “arbitrary” interference with the rights provided under article 17. Consequently, limitations to the right to privacy or other dimensions of article 17 are subject to a permissible limitations test, as set forth by the Human Rights Committee in its general comment No. 27 (1999). That general comment addresses freedom of movement (art. 12), one of the provisions that contains a limitations clause. At the same time, it codifies the position of the Human Rights Committee in the matter of permissible limitations to the rights provided under the Covenant. The permissible limitations test, as expressed in the general comment, includes, inter alia, the following elements: (a) Any restrictions must be provided by the law (paras. 11–12); (b) The essence of a human right is not subject to restrictions (para. 13); (c) Restrictions must be necessary in a democratic society (para. 11); (d) Any discretion exercised when implementing the restrictions must not be unfettered (para. 13); (e) For a restriction to be permissible, it is not enough that it serves one of the enumerated legitimate aims; it must be necessary for reaching the legitimate aim (para. 14); (f) Restrictive measures must conform to the principle of proportionality; they must be appropriate to achieve their protective function; they must be the least intrusive instrument amongst those which might achieve the desired result; and they must be proportionate to the interest to be protected (paras. 14–15); (g) Any restrictions must be consistent with the other rights guaranteed in the Covenant (para. 18).20 18. The Special Rapporteur takes the view that these considerations apply also in respect of article 17 of the Covenant, as elaborations of the notions of “unlawful” and “arbitrary”. Where the textual difference between article 17 and the Covenant provisions that explicitly introduce a limitations test nevertheless matters is in the absence of an exhaustive list of legitimate aims in article 17. Here, the Special Rapporteur calls upon States to justify why a particular aim is legitimate as justification for restrictions upon article 17, and upon the Human Rights Committee to continue monitoring measures undertaken by States parties, including through the consideration of periodic reports and of individual complaints. 20 8 See Human Rights Committee, general comment No. 27 (1999). GE.09-17804