Over the years, the human rights supervisory bodies have made important progress in the determination of the scope and content of the principle of equality and the prohibition of discrimination. Despite the fact that none of the human rights instruments examined here ( ICCPR, ECHR, American Convention and African Charter ) provide a definition of the term ‘discrimination’, the case-law examined provides a clear indication of what constitutes discrimination.

Today, it is well established by these supervisory bodies that not all distinctions in treatment constitute discrimination and that the enjoyment of rights and freedoms on an equal footing does not mean identical treatment in every instance; it is well established in international human rights law that not all distinctions in treatment constitute discrimination. This is summed up by the axiom, ‘persons who are equal should be treated equally and those who are different should be treated differently’ (‘in proportion to the inequality’). As indicated by the Human Rights Committee, ‘the enjoyment of rights and freedoms on an equal footing [?] does not mean identical treatment in every instance.’ Hence, there may be situations in which a different treatment is justified.

Although not all differences in treatment are discriminatory, international law establishes some criteria for determining when a distinction amounts to discrimination. In a nutshell, a distinction is compatible with the principle of equality when it has an objective and reasonable justification, pursues a legitimate aim and there is a reasonable relationship of proportionality between the means employed and the aim sought. These requirements have been stressed by some of the major human rights supervisory bodies. For example, in the words of the Human Rights Committee: ‘Not every differentiation of treatment will constitute discrimination, if the criteria for such differentiation are reasonable and objective and if the aim is to achieve a purpose which is legitimate under the Covenant.’ ( General Comment 18, adopted by the Human Rights Committee ). Differences in treatment (distinction, exclusion, restriction or preference) that comply with the criteria mentioned above are not discriminatory and do not infringe the principle of equality and non-discrimination. Furthermore, certain preferential treatment, such as the special treatment aimed at protecting pregnant women or disabled persons, is not considered discrimination as the purpose is to remedy inherent inequalities. Similarly, affirmative action, defined as measures necessary ‘to diminish or eliminate conditions which cause or help to perpetuate discrimination’ aimed to benefit historically disadvantaged groups within society, must not be considered ‘discrimination’.

The case-law of the various supervisory bodies clearly demonstrates that the grounds on which discrimination is prohibited are not exhaustive; therefore other grounds not explicitly mentioned in the instruments may also be included in the prohibition of discrimination.

Finally, it is important to mention that despite the progress made through the case-law of the different international human rights supervisory bodies, in order to achieve effective protection of the principle of equality and non-discrimination, states must adopt a holistic response to effectively combat discrimination. In this regard, states must, inter alia,provide education to change social practices, undertake institutional changes and take affirmative action for the protection of disadvantaged groups.