the European Convention on Human Rights (Article 14), for example, is now understood to prohibit neutral measures that adversely affect certain minority groups.202 Some human rights treaties go even further and expressly require positive action on the part of states to eliminate discrimination on prohibited grounds (for instance the ICERD and the CEDAW203). However, certain treaties protect equality only in the enjoyment of identified substantive rights (commonly described as “ancillary” protection).204 This means that instead of a free-standing right to equal treatment, protection against discrimination is available only in relation to the application of the other rights protected by the relevant treaty. This can diminish the effect of non-discrimination provisions. Is protection against direct discrimination enough? It is generally understood that the mere fact of having a requirement that there be no difference in treatment between persons in like situations (or “direct discrimination”) is not sufficient to guarantee that some persons or groups will not be disadvantaged. Simple equality of treatment, without regard to the differences between the persons or groups of persons concerned, may operate so as to entrench existing disadvantages. For example, a prohibition on wearing head gear at work imposed on all employees would be equal treatment but would have an impact on groups for whom the wearing of head gear might have some religious or cultural significance. Protecting against indirect discrimination Protection against “indirect discrimination” provides a better opportunity to challenge entrenched discrimination arising out of cultural or other factors. Indirect discrimination is perhaps best explained as a policy, rule or practice that is essentially neutral on its face, in that it applies to everyone, but which may be indirectly discriminatory if it has a disparate impact on people belonging to a particular group.205 The concept of indirect discrimination is now well recognized, including in the sphere of race and ethnic discrimination, and is 202 “The right not to be discriminated against in the enjoyment of the rights guaranteed under the Convention is also violated when States without an objective and reasonable justification fail to treat differently persons whose situations are significantly different”, ECtHR, Thlimmenos v. Greece, Application no. 34369/97, 6 April 2000, para 44. 203 See below, note 209. 204 E.g. Article 2(2) ICESCR and Article 14 ECHR, as opposed to the general non-discrimination provisions in Article 26 ICCPR and Protocol No. 12 ECHR. 205 It is perhaps best explained by looking at the US Supreme Court case that formulated the principle, see U.S. Supreme Court, Griggs v. Duke Power Co., 401 U.S. 424 (1971), 8 March 1971. In Griggs, an employer had an open policy of excluding black applicants from employment. This was replaced by a requirement that candidates have high school qualifications or pass a literacy test. The employment concerned was in the main unskilled and the qualifications sought were not necessary for the carrying out of the work. The effect of applying the qualifications, however, was to disadvantage black candidates as against white. The reason for that was the continuing effects of discrimination in the education system against black pupils, such that a disproportionate number failed to achieve a high school qualification or reach a standard of literacy sufficient to pass the test imposed. Thus, whilst black candidates and white candidates were treated — in a formal sense — equally, black candidates were disadvantaged by the criterion applied and the workforce remained resolutely almost completely white. The US Supreme Court held that such treatment could be discriminatory if the result was such that fewer candidates could comply with the requirement, unless the requirement was necessary for the proper performance of the job. Countering Terrorism, Protecting Human Rights 83