Thus, the specific non-retrogression test is reduced to two criteria; that policies are temporary and that they are necessary and proportionate. The Letter to States notes that the first condition on ‘any proposed policy change’ is that the policy should be temporary. This is similar to the approach under the ICCPR, 69 the European Convention on Human Rights (ECHR), 70 and the American Convention on Human Rights (ACHR). 71 Apart from having proved problematic to enforce and define,72 a condition of ‘temporariness’ denotes a period of exception to, or an aberration from, the more ‘permanent’ state of normality. Such a separation of exception (or emergency) from normality, has been characterised as a ‘fundamental aspect’ of an ‘emergency paradigm’.73 This approach departs from the ICESCR’s previous ‘Business as Usual’ approach to the non-retrogression doctrine by indicating that there is to be an exception to its ‘usual’ applicability. The requirement that policy changes that will affect ICESCR rights be ‘necessary and proportionate’ is also borrowed from the ICCPR, ECHR and ACHR emergency derogations regimes.74 The Letter’s revised test for non-retrogression can be mapped onto the structure of the derogations clauses. Such provisions generally involve a dual-limbed test for determining the legality of a measure.75 The first limb is a threshold test, asking if the requisite circumstances are present for derogation. 76 The second limb focuses on the substance of the measure introduced pursuant to the derogation. The contents of the letter take a similar approach. The first requirement is that there is a temporary economic and/or financial crisis, with elements of ‘a lack of growth’ and ‘inevitable’ adjustments to rights.77 The second limb of the test then uses the ‘necessary and proportionate’ test to assess the substance of the measure. 78 Of course, while there are parallels between the Letter’s derogation-style terminology and structure, and other international and regional human rights frameworks, there is nothing which binds the CESCR to previously established meanings of those terms. There is also a distinctive ‘emergency’ character to the changes. The use of ‘negative lists of exception’ is a familiar feature of emergency governance. 79 By listing those elements of the ICESCR which should not be affected by the crisis (i.e. international cooperation, the protection of the core content of the rights, and non-discrimination), the Committee takes an approach to crisis regulation which is similar to that seen in some national constitutions80 and 69 ICCPR (n 31) article 4. 70 European Convention on Human Rights (1950) article 15(1). Cf the ECtHR case of A v United Kingdom; Fiona de Londras, Detention in the ‘War on Terror’: Can Human Rights Fight Back? (Cambridge University Press 2011) 200–202. 71 American Convention on Human Rights (1969) article 27. Notwithstanding the similarities between the ACHR and ICCPR, many of the constitutions of South American countries set out separate regimes for a diverse range of emergencies, including economic emergencies; Gross and Ní Aoláin (n 7) 42; Brian Loveman, The Constitution of Tyranny: Regimes of Exception in Spanish America (University of Pittsburgh Press 1993) 25. See further; Exception and Emergency Powers, Gabriel L Negretto and Jose Antonio Aguilar Rivera, ‘Liberalism and Emergency Powers in Latin America: Reflections on Carl Scmitt and the Theory of Constitutional Dictatorship’ (1999) 21 Cardozo Law Review 1797. Alan Greene, ‘Separating Normalcy from Emergency: The Jurisprudence of Article 15 of the European Convention on Human Rights’ (2011) 12 German LJ 1764, 1782; Gross and Ní Aoláin (n 7) 171. 72 Greene, ‘Separating Normalcy from Emergency’ (n 71) 1765; Gross and Ní Aoláin (n 9) 174–5. Although these authors do not explicitly endorse this view. 73 74 Human Rights Committee, General Comment 29: States Of Emergency (Article 4) (CCPR/C/21/Rev1/Add11 2001); ECHR (n 66) article 15(1); ACHR (n 67) article 27. All of these regimes require proportionality by reference to the ‘exigencies of the situation’. 75 Greene, ‘Separating Normalcy from Emergency’ (n 68) 1766. 76 Ibid. 77 Letter to States (n 1, Annex I), 5.. Letter to States (n 1, Annex I), 6. The two other conditions listed in paragraph 6 – the requirement of non discrimination and respect for the minimum core of the rights – might be thought of as ‘absolute’ or non-derogable provisions. 78 79 Gross and Ní Aoláin (n 7) 58. 80 ibid eg Nicaragua, Portugal, South Africa, Peru. 9