10 C. R  elationship among treaty bodies and with other United Nations human rights mechanisms Relationship among treaty bodies The principal means of communication among treaty bodies is the annual meeting of their Chairs and the related activities in between sessions. The Chairs of the treaty bodies meet annually in June to discuss matters of common interest and to promote the harmonization of working methods. Over the years, their potential to promote the harmonization of working methods across treaty bodies has become stronger. At their meeting in 2011, the Chairs recommended that they should have the possibility of adopting measures on working methods and procedural matters that were common across treaty bodies and that had already been discussed by all treaty bodies. Treaty bodies would then implement such measures, unless a body subsequently disassociated itself from the recommendation.6 The role of the Chairs in harmonizing working methods recently received a boost from the General Assembly, through its resolution on strengthening and enhancing the effective functioning of the human rights treaty body system, which encouraged treaty bodies “with a view to accelerating the harmonization of the treaty body system, to continue to enhance the role of their Chairs in relation to procedural matters, including with respect to formulating conclusions on issues related to working methods and procedural matters, promptly generalizing good practices and methodologies among all treaty bodies, ensuring coherence across the treaty bodies and standardizing working methods”.7 In addition, treaty bodies sometimes organize joint meetings either during formal sessions or in between sessions, on occasion with the assistance of NGOs or academic institutions. The Optional Protocol to the Convention against Torture requires the Subcommittee and the Committee against Torture to hold their sessions simultaneously at least once a year (art. 10.3), which in practice has led to these two bodies meeting annually in formal joint meetings. Relationship between the treaty bodies and the universal periodic review mechanism The universal periodic review is a mechanism by which the human rights record of all United Nations Member States is examined by a working group of States every four and a half years. It is an intergovernmental mechanism intended to complement and not duplicate the work of other human rights mechanisms. The basis of the review, as established in Human Rights Council resolution 5/1 of 18 June 2007, is: (a)  the Charter of the United Nations; (b)  the Universal Declaration of Human Rights; (c) human rights instruments to which the State is a 6 7 A/66/175, para. 21. Resolution 68/268 of 9 April 2014, para. 38.