A/HRC/10/48 page 10 relevant considerations. Notwithstanding such flexibility, the means through which the Convention is given effect must be appropriate in the sense of producing results that are consistent with the full discharge of the obligations of the State party. In all cases, in accordance with article 4, paragraph 3, States are required to closely consult and actively involve persons with disabilities through their organizations in the development and implementation of legislation and policies to implement the Convention. D. Measures for implementation 30. It is a basic principle of international law that a State party to an international treaty must ensure that its own domestic law is consistent with what is required by the treaty.26 It follows that, except in the rare cases in which the rights and principles of the Convention are already protected by domestic law, States parties are required upon ratification to make appropriate changes to domestic law to ensure its conformity with the Convention.27 This duty applies also to States where the Convention is part of national law as “incorporation by itself does not avoid the need to ensure that all relevant domestic law, including any local or customary law, is brought into compliance with the Convention”28 and also to States where the Convention enjoys constitutional status and above. Accordingly, article 4, paragraph 1 (b), of the Convention obliges States parties to “take all appropriate measures, including legislation, to modify or abolish existing laws, regulations, customs and practices that constitute discrimination against persons with disabilities”. In order to adequately implement the Convention, one of the first steps that States need to undertake is a comprehensive review of the national legislation and policy framework. Treaty bodies have often explicitly recommended that States parties undertake such a review29 and that it be rigorous and “consider the Convention not only article by article, but also holistically, recognizing the interdependence and indivisibility of human rights”.30 31. According to information provided for this study, numerous States parties and signatories to the Convention have embarked on an internal review of legislation for compliance, the scope and depth of which appear to vary significantly. While in only a few States parties such a 26 See for example United Nations Department of Economic and Social Affairs, OHCHR and the Inter-Parliamentary Union, From Exclusion to Equality: Realizing the Rights of Persons with Disabilities (Geneva, 2007), available at: http://www.ohchr.org/Documents/Publications/ training14en.pdf. 27 Human Rights Committee, general comment No. 31, para. 13. 28 See Committee on the Rights of the Child, general comment No. 5 (2003) on general measures of implementation of the Convention on the Rights of the Child (arts. 4, 42 and 44, para. 6), para. 20. 29 See for example CEDAW/C/NIC/CO/6, para. 8 and CCPR/C/79/Add.21, para. 18. 30 Committee on the Rights of the Child, general comment No. 5, para. 18.