Equality as Legal Argument

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by Janneke Gerards


1. Introduction

Equality is considered a principle of fundamental importance, which should form the basis of each legal system and which should be respected at all times by legislative, executive and judicial authorities. It is equally clear, however, that it is impossible to realise complete equality in practice. It is inevitable that every law differentiates between persons, groups or factual situations, just as it cannot be expected that everybody treat all other persons in the same way. Besides, it is often contended that complete equality is not even desirable, because there would then be no scope for differences in personal ambitions, abilities or needs (e.g. Blackstone 1967, p. vi). There is thus a clear tension between the search for equality and the need to treat persons and cases differently. This tension is described as the ‘paradox of equality’ (e.g. Tussman/TenBroek 1949, p. 344) or the ‘dilemma of difference’ (Minow 1990, p. 20). The equality paradox is central to the legal understanding of the principle: one of the main tasks of legislators and courts is to find practicable solutions for this paradox in concrete situations.
In order to provide some insight in the meaning of the legal principle of equality and the related equality paradox, we will hereinafter discuss some important legal notions and distinctions. First, we will explain a few relevant terms and distinctions, such as the distinction between formal and substantive equality and between equality before the law and equality of the law (section 2 and 3). After describing the constituting elements of the legal principle of equality (section 4), we will then explore the issue of when cases or persons are equal (descriptive equality, section 5) and when they ought to be treated equally (prescriptive equality, section 6). Both questions are of essential importance to the use of equality as an argument in the legal discourse.

2. Formal, procedural and substantive equality

In the legal discourse, formal inequality means that two cases are treated unequally, whereas formal equality means that two cases are treated equally. Whether or not the concrete cases show any substantive differences or similarities does not seem to be of any significance to the legal notion of formal equality. This can be illustrated with an example from the case-law of the European Court of Human Rights (ECHR), which until 2000 used a purely formal conception of equality. In the case of Stubbings v. United Kingdom, the ECHR had to give a judgement on a complaint by several British women who had been a victim of sexual abuse when young (ECHR 22 October 1996, Reports 1996-IV). In later years they suffered from psychological problems, but only realised after a long time that the origin of these problems lay in the sexual abuse. In England there was a period of limitation of six years for personal injury proceedings, which began to run when the victim reached the age of eighteen. Any possible claim was thus statute barred, so that according to English law the applicants could no longer ask for damages. The applicants put to the ECHR that the uniformity of the limitation rules infringed the principle of equal treatment: they were of the opinion that there was a clear difference between the specific psychological damage that they had suffered and other cases of deliberate harm. The ECHR decided otherwise: “The Court observes […] that as between the applicant and victims of other forms of deliberate wrongdoing with different psychological after-effects, there was no disparity in treatment, because the same rules of limitation are applied to each group.” (§ 73) Since the cases were treated formally equal, the Court did not deem it relevant that the cases presented to it might be considered to be unequal in fact. Consequently, it did not find a violation of the principle of equal treatment in this case.
The legal principle of substantive inequality does take such factual differences into account indeed. In legal argument, substantive inequality means that substantively unequal cases are treated in the same way. Substantive inequality obviously does not imply a formal difference in treatment – the cases are after all treated the same. Still, formal equal treatment can sometimes constitute inequality: inequality in result, caused by the fact that insufficient account is being taken of the differences that in fact exist between groups, persons or situations (e.g. Minow 1990 and Oppenheim 1970). For this reason substantive equality is often termed equality in result, whereas formal equality might be described as equality in treatment. Most courts (since 2000, with the case of Thlimmenos v. Greece (Reports 2000-IV), even the ECHR) now seem to accept that the legal equality principle is not only concerned with cases of formal unequal treatment, but also with cases of substantive unequal treatment. This is expressed, for instance, in a formulation such the following: “[…] [The principle of equal treatment] not only requires that persons in a similar situation must be treated in an equal manner but also requires that persons whose situations are significantly different must be treated differently […]” (ECHR 6 January 2005, Hoogendijk v. the Netherlands, p. 20).
A third important legal concept is that of procedural equality, which is closely related to the concept of equal opportunities. Unlike formal equality, procedural equality takes some account of the differences that exist between individuals, more specifically: of their differences in opportunities. Unlike substantive equality, however, complete equality in result is not the goal sought for. Even if people start from the same position and have equal opportunities, the final results that they achieve can differ (e.g. Schaar 1967). The distinction between substantive and procedural equality can be elucidated by the example of preferential treatment or affirmative action. According to the relevant literature and case-law, a policy of preferential treatment may be introduced for (at least) two different reasons (see further Fredman 2002, p. 126 ff). In the first place, such a policy may be used to realise proportional representation of men and women in all social functions. To this effect, a quota is usually set for the participation of women in certain functions, supported by a policy giving direct priority to women applying to such a function. This kind of policy thus strives for substantive equality or equality in result: regardless of any relevant or irremovable differences between the sexes, men and women should find themselves in completely equal positions in the end.
A policy of preferential treatment that is directed at equality of opportunities or procedural equality has a different purpose. Such a policy will usually start from the given fact that women find themselves in a disadvantageous position compared to men as a result of long-standing discrimination, historically grown social barriers and negative stereotypes. Even if women are qualified equally well as men and show equal abilities and talent, they will therefore often not be in a position to compete with men on an equal footing. Procedural preferential treatment policies aim at removing social and practical barriers (e.g. by means of granting priority to women with regard to child care places) and at combating persistent and negative forms of stereotyping, thus striving towards the creation of equal opportunities for women to participate in society. In the end, such policies might contribute to equal representation of men and women in all functions, but not necessarily so. Even if all barriers are reduced, biological differences or differences in preference might stand in the way of complete substantive equality between men and women.

3. Equality before the law and equality of the law

In defining the legal principle of equality, a further distinction is often made between equality before the law and equality of the law. The principle of equality before the law (confusingly sometimes also termed formal equality) requires that a rule be applied to all cases which satisfy the conditions laid down by the rule (Oppenheim 1970); thus, the requirement corresponds with that of a proper application of the rule. The principle of equality before the law does not seem to add much to the concept of the generality of legislation or the general principle of consistency (Leibholz 1925, p. 31 and Perelman 1963, p. 10 and 37). It might be submitted, on the other hand, that these concepts themselves flow from the equality principle and that, for that reason, the principle of equality before the law is still of great importance (Chemerinsky 1983, p. 581).
The principle of equality before the law does not guarantee equality as regards the content of legislation (e.g. Lucas 1965). It is unavoidable that each legislative act distinguishes between groups or cases. The very act of legislating will inevitably result in a distinction between those groups or cases that fall under the scope of the legislation and those who do not. In addition, many acts will contain further, specific distinctions between groups, cases or classes. The principle of equality of the law (sometimes also termed substantive equality) concerns the reasonableness of such legislative distinctions and classifications. The connection between the principle of equality and the notion of reasonableness or justice will be further explored in Section 6.

4. Elements of the Concept of Equality: Plurality and Comparison

The legal concept of equality is a comparative concept that presupposes plurality. The element of plurality is relevant at two different levels. Firstly, equality presupposes plurality of subject, which means that a law, decision or act must always concern at least two different persons, groups or cases. Secondly, equality presupposes plurality of object, which means that the relevant persons, groups or cases must be given a different treatment. The comparative element is closely related to this: the equality principle requires a comparison to be made, either between the treatment that is given to the relevant groups, persons or cases, or between the groups, persons and cases themselves. Thus, the equality principle is relevant as soon as a certain case, group or person is treated in a different way than another case, group or person (see also Aristotle, Nicomachean Ethics, reprinted in Pojman/Westmoreland 1997, p. 20).

5. When are Cases ‘Equal’? – Descriptive Equality

An important question relating to the legal principle of equality, which flows logically from its comparative character, is when can cases be considered ‘equal’? It is evident that ‘equality’ does not require cases to be identical. Complete equality is in fact not even possible: if two things were completely identical, they would actually be the same thing (Westen 1990, p. 25). Indeed, even two apparently identical ping-pong balls are made up of different molecules and take up different space (Pojman/Westmoreland 1997, p. 2). At the same time, all persons, things and cases share certain similarities. Even such completely different things as a ping-pong ball and a human being are made up of molecules and take up a certain space. Paradoxically, thus, cases are always both comparable and non-comparable, or both equal and unequal (Perelman 1963, p. 16 and Alexy 1985, p. 362). In order to make a meaningful comparison between cases, persons and groups, and to give a meaningful answer to the question whether two or more cases are ‘equal’ or ‘comparable’, it is therefore necessary to establish what characteristics or features of the cases, persons or groups are relevant for the comparison (e.g. Oppenheim 1970). Hence, the element of comparison presumes the presence of a suitable criterion or standard to determine the relevance of similarities and differences (Westen 1990, p. 30).<span id="fck_dom_range_temp_1239714796921_315" />
The choice of a suitable standard of comparison depends on the perception of certain characteristics as relevant for the comparison. In deciding between job applicants for a management function, for example, differences in work experience and education may be important, whereas differences in hair colour or food preference will mostly be irrelevant. In such a case, work experience and education would seem to be the most appropriate standards of comparison. When choosing a standard of comparison, one should thus let oneself be guided by the direct context and aims of the difference in treatment. Indeed, it can be taken as a rule that the proper standard of comparison can be detected by formulating the reason for making a distinction.
If a suitable standard of comparison is chosen, it is relatively easy to determine whether cases are comparable or ‘equal’. The standard need only be applied to the factual situation to see whether or not the relevant characteristics are present. The result of this operation is a descriptive or factual determination of equality: by pointing to the standard of comparison and to the facts of the case, it can be determined that the cases (or the treatment) are factually or descriptively equal or unequal (Oppenheim 1970).

6. When Should Cases Be Treated Equally? – Prescriptive Equality

Thus, we have shown that the determination of equality or inequality is descriptive in character: it is only determined that two cases are equal or unequal in fact. A conclusion as to how these cases should be treated (differently or similarly) is still to be reached. In order to do so, it is necessary to reason from an ‘is’ to an ‘ought’ – from the fact that two cases are relevantly equal or unequal (descriptive or factual equality), it must be reasoned that they ought to be treated in a certain way (prescriptive, normative or evaluative equality). The relationship between descriptive and prescriptive equality is particularly complicated and is closely related to the discussion about the relation between equality and formal and substantive justice (cf. Oppenheim 1970 and Westen 1990).
Some practical problems related to the notion of prescriptive equality may be illustrated by the example of an entry policy maintained by the owner of a dancing. If the owner wants to discourage coloured persons from frequenting his dancing, he can try to achieve this goal by asking such a person to pay a considerably higher entrance fee than white persons. This difference in treatment is based on a difference in skin colour that, in the light of the aims of the owner, is without doubt relevant. If skin colour is used as a standard of comparison, it must therefore be concluded that coloured persons and white persons are descriptivelyought to be treated differently and that, for that reason, a court confronted with this case simply should consider the difference in treatment compatible with the equality principle? Or does the equality principle also require that the court pay attention to the reasonableness of the standard of comparison, or the proportionality of the difference in treatment in relation to the factual differences between white and coloured persons?

unequal. Does this conclusion then inevitably imply that these persons

In legal theoretical writing, different answers have been given to such questions. It appears that at least four approaches can be distinguished:
1)   Descriptively equal cases ought to be treated equally, descriptively unequal cases ought to be treated unequally.
2)   Descriptively equal cases ought to be treated equally, descriptively unequal cases ought to be treated unequally, according to their degree of inequality.
3)   Descriptively equal cases ought to be treated equally, unless unequal treatment can be justified on the basis of objective and reasonable arguments. Descriptively unequal cases ought to be treated unequally.
4)   Descriptively equal cases ought to be treated equally, unless unequal treatment can be justified on the basis of objective and reasonable arguments. Descriptively unequal cases ought to be treated unequally, according to their degree of inequality.

The first approach is purely formal in character. According to this approach, the equality principle is a principle of consistency, or a prohibition of arbitrariness: if one has acted in a certain way in one case, the same line of action ought to be taken in each comparable case. Indeed, this approach forms the core of both the conception of formal equality and formal justice and it is reflected in the principle of equality before the law (see e.g. Perelman 1963, p. 50, Westen 1982, p. 558 and Hare 1978, p. 219; see for a practical example the case of Stubbings mentioned in section 2). Whether or not a case of formal equal treatment is reasonable in substance, is a question that is left unanswered by this approach. For that reason, some legal writers have argued that, apart from the formal principle of equality, a substantive principle must be distinguished (e.g. Oppenheim 1970 – equality of the law). With respect to this principle, the conception of reasonableness plays a certain role (Lucas 1965; cf. also Hare 1978, p. 219). There is no consensus, however, as to how this concept should be connected to the equality principle. This is clear from the differences between the second, third and fourth approaches.
The second approach starts from the same purely formal principle of equality as the first approach: it simply states that ‘equal cases ought to be treated equally’. In reaching this prescriptive conclusion, this approach seems to rely on an element of formal justice, just like the first approach. It assumes that equal treatment of equal cases is formally just, and that therefore equal cases ought to be treated equally (Aristotle, Nicomachean Ethics, reprinted in Pojman/Westmoreland 1997, p. 20; cf. also Perelman 1963, p. 16).
Some authors have argued, however, that the assumption that equal cases should always be treated equally is erroneous. Unequal treatment of equal cases may be justified by reasons that are unrelated to the relevant differences and similarities between the cases. It may for instance be advisable to treat relevantly equal groups formally differently in order to achieve substantive or procedural equality (equality in result or of opportunities – cf. the affirmative action policies mentioned in section 2), or to serve purely administrative purposes (e.g. Greenawalt 1983, p. 1174). It is also sometimes argued that the reasonableness of equal treatment depends on whether a just standard of comparison has been used in determining the equality of the cases. If the opinion that two cases are relevantly equal is based on an unreasonable standard of comparison, it may be substantively unjust to treat the cases equally (cf. e.g. Lucas 1965 and Perelman 1963, p. 17). Finally, it has been contended that the notion of freedom or liberty may override the equality ideal: in some cases, considerations of liberty (expressed, for instance, in the freedom of contract) may justify that an individual does not treat all equal persons completely equally (Lucas 1965). In this view, there is thus a clear and explicit link between the equality principle and a substantive conception of justice. Such a connection finds clear expression in the third and fourth approaches to prescriptive equality, which both require a further examination to be made into the substantive reasons for unequal treatment of equal cases.
According to the Aristotelian formula – described above as the second approach to prescriptive equality – the equality principle further requires that some degree of proportionality exist between the factual differences between the cases and the difference in treatment. The element of proportionality would seem to reflect an element of substantive justice: if a difference in treatment does not stand in a proportional relationship to the differences between the cases, it is substantively unjust (cf. Aristotle, Nicomachean Ethics, reprinted in Pojman/Westmoreland 1997, p. 20 and 23; see on this also Perelman 1963, p. 32 and 54).
The first and third approaches deny the need of such an element of proportionality. For the first approach, this can be explained by the wish to completely separate the concepts of equality and substantive justice: the fact that unequal cases should be treated unequally is purely considered a demand of consistency or formal justice. In the third approach, it is more difficult to explain the lack of an element of proportionality. It might be that an implicit assumption is made to the effect that it is always substantively just to treat different cases in a different manner, regardless of any amount of disproportionality between the treatment and the differences between the cases. This is not, however, a very convincing assumption, especially as an element of substantive justice is visible with respect to the different treatment of equal cases indeed. It is probably for this inconsistency in the underlying assumptions that the third approach is not often used in legal practice.
Finally, the fourth approach accepts a fusion between the principle of equality and a substantive conception of justice. According to this approach, an element of substantive justice is always needed to reason from descriptive to prescriptive equality, or from an ‘is’ to an ‘ought’ (Westen 1990, p. 70). The reason adduced in support of this is that it is simply not possible to conclude from the fact that two cases are factually equal or unequal that they ought to be treated in a certain way, without presupposing substantive moral or legal standards (see e.g. Westen 1982). If cases are equal, an assessment should therefore be made as to whether it is substantively just to treat them differently (cf. Westen 1990, p. 71). The same is true if the cases are relevantly unequal – at least it should then be established that there is a sufficient degree of proportionality between the differences between the cases and the differences in treatment. In addition, it is sometimes contended that the fourth approach requires a determination to be made as to the reasonableness or justice of the standard of comparison. Indeed, different treatment of equal or unequal cases may be unacceptable if the standard of comparison itself is unjust or unreasonable – the example of the owner of the dancing clearly shows this.
Thus, the fourth approach would seem to boil down to a test of substantive justice: regardless of whether the cases are descriptively equal or unequal, the approach always requires an assessment of the justice of treating them in a certain way (Westen 1982).
The fourth approach is often used in legal practice, although the concept of substantive justice is then usually replaced by the terminology of ‘reasonableness’. It is regularly stated in case-law and legal texts that equal or unequal treatment should be ‘reasonable’ in order to be compatible with the equality principle, or that a difference in treatment is only allowable if it is ‘objectively and reasonably justified’ (see for examples Gerards 2005). This is usually taken to mean that the reason for treating the cases differently or equally must be justifiable, and that there must be a reasonable relation between the reason given for the treatment and the interests that are negatively affected by it (Gerards 2005). This approach also seems to offer a solution to the ‘paradox of equality’ or the ‘dilemma of difference’ which was mentioned in section 1: cases ought to be treated equally or unequally if it is reasonable to do so.
The test of reasonableness, however, does still not form a real solution to the dilemma. More readily, it might be described as a restatement of the problem, since the answer to the question if a difference in treatment is acceptable then comes to depend on the interpretation of the concepts of ‘reasonableness’ and ‘substantive justice’. Readers interested in these topics may be referred to the specific entries ‘Fairness’, ‘Justice’, ‘Justification’ and ‘Rational and reasonable’.

Related entries

AristotleEqualityEquityFairnessJusticeJustificationLegitimacyLegitimateChaim PerelmanPractical Argumentation in the Justification of Judicial DecisionsRational and reasonableWeighing and balancing in the law.


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