Chief Justice Ma: A. INTRODUCTION 1. This appeal involves principally an analysis of the appropriate test to be used when dealing with alleged discrimination under the Sex Discrimination Ordinance[1] and of its application to the facts of the case. The guarantee of equality is found in the Basic Law.[2] Article 22 of the Hong Kong Bill of Rights[3] states:- “Equality before and equal protection of law All persons are equal before the law and are entitled without any discrimination to the equal protection of the law. In this respect, the law shall prohibit any discrimination and guarantee to all persons equal and effective protection against discrimination on any ground such as race, colour, sex, language, religion, political or other opinion, national or social origin, property, birth or other status.” 2. The present case is concerned with custodial discipline in penal establishments. Section 9 of the Hong Kong Bill of Rights Ordinance states:- “Armed forces and persons detained in penal establishments Members of and persons serving with the armed forces of the government responsible for the foreign affairs of Hong Kong and persons lawfully detained in penal establishments of whatever character are subject to such restrictions as may from time to time be authorized by law for the preservation of service and custodial discipline.” 3. A constitutionality issue also arises in this appeal under Article 25 of the Basic Law, but as we shall see, this is of less importance than the issue of discrimination under the SDO. A.1 The facts 4. The facts are straightforward. In March 2012, the appellant, a politician and activist who is widely known as “Long Hair”, was convicted in the Magistrates’ Court of charges of criminal damage (2 charges) and disorderly behaviour (2 charges) and sentenced concurrently to a total term of imprisonment of 2 months. On appeal, in June 2014, the conviction for one of the charges of criminal damage was quashed and the totality of his sentence was reduced to 4 weeks. At Lai Chi Kok Reception Centre, he was required to have his hair (then about 80 cm long) cut pursuant to Standing Order 41-05 (“SO 41‑05”). This standing order,[4] which appears to be the only provision dealing with the length of hair of prisoners, applies to both male and female prisoners:- “1. The hair of all male convicted prisoners will be kept cut sufficiently close, but not close clipped, for the purposes of health and cleanliness unless the prisoner himself requests it. 為保健康及清潔，所有已男子定罪囚犯的頭髮須盡量剪短，但不用剪陸軍裝，除非囚犯本身要求如此。 2. Upon request, female prisoners will have their hair cut especially before discharge or production in court. Except as recommended by MO, a female prisoner’s hair shall not be cut shorter than the style on admission without her consent. 若女子囚犯申請剪髮，須為其作出安排，特別是在獲釋前或到法庭應訊前。未經囚犯同意，不可把其頭髮剪至較進入院所時的髮型更短，但如醫生建議這樣做，則屬例外。” 5. It was the decision to require the appellant to cut his hair (the Decision) that formed the basis for his application for leave to apply for Judicial Review. Essentially, the appellant’s complaint is that he was discriminated against on account of his sex: while the hair of male convicted prisoners like him had to be kept sufficiently close, by contrast female prisoners had a freer choice and, except as recommended by a Medical Officer, their hair could not be cut shorter than the style on admission to prison without their consent. In the language of the relevant provision of the Ordinance with which this appeal is concerned, the appellant says he has been treated less favourably than female prisoners. A.2 The proceedings below 6. Before Au J, the Judicial Review challenge by the appellant was based on 4 grounds, namely, discrimination under the SDO, breach of the equality provisions under Article 25 of the Basic Law, Wednesbury unreasonableness and breach of the dignity provision in Article 6(1) of the Bill of Rights. The judge held[5] in favour of the appellant on the first 2 grounds, did not think it was necessary to deal with Wednesbury unreasonableness and rejected the 4th ground. Declarations were made that the Decision constituted direct sex discrimination under the SDO and also violated Article 25 of the Basic Law. An order was also made quashing the Decision. 7. On the respondent’s appeal, the Court of Appeal[6] allowed the appeal and set aside Au J’s order. There being no Respondent’s Notice, the Court of Appeal only dealt with the sex discrimination and Article 25 issues. Like the CFI Judgment, the Court of Appeal concentrated mainly on the sex discrimination issue. These are the same issues before us. A.3 The certified question 8. Leave to appeal to the Court of Final Appeal was refused by the Court of Appeal,[7] but on 13 August 2019, the Appeal Committee[8] granted leave to appeal to the appellant on the following question of law:- “Whether the Standing Order 41-05 issued by the Commissioner of Correctional Services requiring all male prisoners but not female prisoners to have their hair cut ‘sufficiently close’ (‘盡量剪短’): (1) constitutes direct discrimination under section 5(1)(a) of the Sex Discrimination Ordinance, Cap 480 (‘SDO’) and is therefore unlawful under section 38 of the SDO; and/or (2) is inconsistent with Article 25 of the Basic Law of the HKSAR and is therefore unconstitutional?” 9. It is convenient to deal first with the issue of sex discrimination under the SDO before dealing with the constitutionality issue under Article 25 of the Basic Law. I start by discussing the approach in discrimination cases under the SDO before applying the relevant principles to the facts in the present case. I will then deal with the Article 25 issue. B. THE APPROACH IN DISCRIMINATION CASES UNDER THE SDO B.1 Relevant statutory provisions 10. The SDO is fairly comprehensive in dealing with many aspects of sex discrimination including sexual harassment. The Ordinance also makes provision for the establishment and operation of the Equal Opportunities Commission. In relation to sex discrimination, there are set out detailed provisions relevant to employment (Part 3) and to other miscellaneous fields. The basic concept of sex discrimination is defined in Part 2 of the Ordinance in s 5(1):- “Sex discrimination against women (1) A person discriminates against a woman in any circumstances relevant for the purposes of any provision of this Ordinance if— (a) on the ground of her sex he treats her less favourably than he treats or would treat a man; or (b) he applies to her a requirement or condition which he applies or would apply equally to a man but— (i) which is such that the proportion of women who can comply with it is considerably smaller than the proportion of men who can comply with it; (ii) which he cannot show to be justifiable irrespective of the sex of the person to whom it is applied; and (iii) which is to her detriment because she cannot comply with it.” Although this provision refers to discrimination against women, it equally applies to discrimination against men: see s 6(1). 11. Section 5(1)(a) of the SDO deals with what is known as direct discrimination. Section 5(1)(b) (in particular sub‑paragraphs (i) and (iii)) deal with indirect discrimination. These two types of discrimination were discussed by this Court in QT v Director of Immigration.[9] Further, in R (E) v Governing Body of JFS,[10] the difference was put in the following way:- “56. The basic difference between direct and indirect discrimination is plain: see Mummery LJ in R (Elias) v Secretary of State for Defence [2006] 1 WLR 3213, para 119. The rule against direct discrimination aims to achieve formal equality of treatment: there must be no less favourable treatment between otherwise similarly situated people on grounds of colour, race, nationality or ethnic or national origins. Indirect discrimination looks beyond formal equality towards a more substantive equality of results: criteria which appear neutral on their face may have a disproportionately adverse impact upon people of a particular colour, race, nationality or ethnic or national origins.” We are in this appeal only concerned with direct discrimination.[11] 12. The discrimination provisions are relevant to the facts of the present case by reason of s 38(1) of the Ordinance which states that it is unlawful for the Government to discriminate in the performance of its functions or in the exercise of its powers. B.2 The approach 13. In the context of the present case, what must be demonstrated by the appellant is that on the ground of his sex he has been treated by the respondent less favourably than the respondent has treated or would treat a female prisoner in similar circumstances. I will refer to a person in the position of the appellant as “the complainant” and the person who is alleged to have discriminated simply as “the discriminator”. 14. In Secretary for Justice v Chan Wah,[12] a case involving alleged sex discrimination in the context of elections for village representatives, this Court adopted the “but for” test articulated by Lord Goff of Chieveley in R v Birmingham City Council, ex p Equal Opportunities Commission:[13] “There is discrimination under the statute[14] if there is less favourable treatment on the ground of sex, in other words if the relevant girl or girls would have received the same treatment as the boys but for their sex”. The test was reaffirmed in James v Eastleigh Borough Council and stated to be an objective, not subjective, one.[15] 15. This test, simply stated, however requires a little further elaboration in terms of setting out the necessary steps before a finding of sex discrimination can be established. Here, the 4 step approach contained in the speech of Baroness Hale of Richmond in R (European Roma Rights) v Prague Immigration Officer[16] is helpful. Notwithstanding the fact that was a case involving discrimination under the Race Relations Act 1976, the approach is logical and, translated to the context of sex discrimination, can be stated as follows:- (1) There must be a difference in treatment between one person, the complainant (in our case male prisoners; more specifically the appellant) and another person, real or hypothetical, from a different sex group, the compared person (in our case, female prisoners). (2) The relevant circumstances between the complainant and the compared person are the same or at least not materially different. (3) It must then be shown that the treatment given to the complainant is less favourable than that given to the compared person. (4) The difference in treatment is on the basis of sex. Although there may be some overlap in these steps, it is useful to break down the analysis in this way. B.3 Difference in treatment 16. As to para 15(1), this can be identified in most cases, by referring to the essential complaint made by the complainant. Thus, in the present case, the appellant’s complaint is that he was treated differently to female prisoners, not being given the choice they had and accordingly being required to have his hair cut. B.4 Comparing like with like 17. In relation to the requirement in para 15(2), what is needed to be shown is that when embarking on the comparison exercise, it is important to compare like with like and to view the matter in proper context. It is only when one is comparing like with like that one can then move to the next critical inquiry of asking whether there is less favourable treatment that has been accorded by the discriminator to the complainant. This reflects s 10 of the SDO that when making comparisons for the purpose of the s 5(1) exercise, “the relevant circumstances in the one case are the same, or not materially different, in the other.” In a nutshell, “there must be no less favourable treatment between otherwise similarly situated people on grounds of”[17] sex. In the present case, the appellant is comparing himself with female prisoners. B.5 Less favourable treatment 18. This is the requirement in para 15(3) above. It is expressly referred to in s 5(1)(a) of the SDO and will almost invariably be the focal point in discrimination cases. The mere fact there is a difference in treatment between the complainant and the compared person will not of itself amount to unlawful discrimination; there must be shown less favourable treatment given to the complainant. Less favourable treatment is the essence of discrimination. As Lord Walker of Gestingthorpe put it in R (Carson) v Secretary of State for Work and Pensions,[18] “Discrimination on the ground of sex or race demeans the victim by using a sexual or racial stereotype as a sufficient ground for unfavourable treatment.” While in many situations (obviously when one is comparing like with like), such as in the cases dealing with selection requirements for secondary schools,[19] it may be relatively easy to identify less favourable treatment, this is not always so and a careful evaluative assessment will sometimes be required. Of course, in the assessment of this factor, context is all important. In addition, the question should be answered objectively and not subjectively from the point of view of the complainant. As was put by Dillon LJ in the Court of Appeal in R v Birmingham City Council,[20] “[T]he loss, because of sex, of the chance of getting something which is reasonably thought to be of value is enough to constitute sex discrimination.” Lord Goff of Chieveley in the House of Lords in the same case also referred to “reasonable grounds”.[21] That the test is objective was, as stated earlier, also confirmed in James v Eastleigh Borough Council.[22] The reference to “reasonable grounds” highlights the requirement in discrimination cases, once different treatment is shown, to evaluate objectively the grounds and factual criteria explaining why the discriminator acted as he or she did: see JFS.[23] 19. In some cases (such as the present) the discriminator will refer to some underlying objective, policy or reason to demonstrate that the difference in treatment does not amount to less favourable treatment. Apart from of course articulating such objective, policy or reason, it will be necessary to demonstrate that the difference in treatment is logically and reasonably connected to it. Only then will it be possible to take such objective, policy or reason into account in order to determine whether or not there has been less favourable treatment. I have found useful the analysis of Weatherup J in Re McMillen, a case involving length of hair restrictions in schools:-[24] “[21] Secondly, the approach to less favourable treatment. There are interrelated questions as to whether the restriction on appearance could properly be justified by the objective of the code and whether the restriction, in the context of the code as a whole, resulted in less favourable treatment for the boys. The initial assessment is made with reference to the objectives of the code in question. In other words, it is not a question of making comparisons with other people who would adopt the dress or appearance that is prohibited, but rather it is a question of assessing the restrictions that have been introduced against the objectives of the code. That, of course, requires one to identify the objectives. This approach is not to judge the quality of the reasons or the motives for introducing the code, because there can be no justification if there is direct discrimination, but it is to consider whether there is less favourable treatment by establishing a legitimate objective for the code and then assessing the treatment of those affected against the standard that has been adopted by the code to determine whether males or females are disadvantaged compared to each other. Thus in the employment context the objective of the restrictions may be to promote a concept of smartness on commercial grounds and that has been accepted as a legitimate objective. The code might define the particulars of smartness for commercial reasons, for example by no ponytails for men or collar and tie for men. The issue is not concerned with the extent of the general use of the prohibited items but whether a package that includes requirements which differ between men and women, is directed at the objective of the code and whether it imposes a particular disadvantage on one or other sex. In schools the context is different and the objective will be different.” This approach also has relevance when considering what is known as packaging.[25] 20. It is, however, important here to point out that while it is crucial to look at the grounds and factual criteria explaining the difference in treatment, it is irrelevant to consider the motive of the discriminator; in other words, in cases of direct discrimination, justification in this sense is irrelevant.[26] As Lord Kerr of Tonaghmore JSC said in JFS,[27] there is “the need to recognise the distinction between, on the one hand, the grounds for the decision (what was the basis on which it was taken) and on the other, what motivated the decision‑maker to make that decision.” 21. In the present case, as we shall see, the respondent explains the different treatment of male and female prisoners by reference to the policy of custodial discipline. It is said that custodial discipline requires the imposition of reasonable uniformity and conformity in appearance among inmates, and in this context, the respondent adopts the requirements stated in SO 41‑05. The difference in treatment of men and women in that standing order is explained by the underlying fact that it is said to reflect conventional standards of appearance in society. Accordingly, it is said there is no less favourable treatment of male prisoners. 22. The respondent’s arguments will have to be looked at more closely later, but it can be accepted that in some situations, resort to societal or conventional standards may be legitimate. One example of this is where for reasons of privacy and decency, different rules may exist between men and women. The segregation of men and women in different toilets provides a common scenario. So too the difference in cross gender rub down searches in prisons. In R (On the Application of James Dowsett) v Secretary of State for Justice[28], a policy of rub down searches in prisons was challenged as being directly discriminatory. In that case, male prisoners were subject to searches by both male and female prison officers whereas female prisoners could only be searched by female officers. The challenge in the case was made by a male prisoner. Silber J held this difference not to be discriminatory because on the facts there had to be considerations of privacy and decency.[29] In Conway v Canada,[30] in relation to frisk searches in circumstances similar to Dowsett, the Supreme Court of Canada held there was no violation of s 15 of the Canadian Charter of Rights and Freedoms.[31] It was said by La Forest J,[32] “the historical trend of violence perpetrated by men against women is not matched by a comparable trend pursuant to which men are the victims and women the aggressors”. 23. It is unnecessary (and unwise) to attempt to define the limits of the factor of conventional standards when considering the aspect of less favourable treatment, but it can be accepted that in certain circumstances it may be a relevant consideration. Much of course depends on the precise circumstances of any given case and the evidence before the Court. 24. There are also raised by the parties aspects of what are known as packaging and stereotyping, and it is to these facets I now turn. B.6 Packaging 25. It is the respondent’s[33] contention that when determining discrimination, it is wrong merely to compare one item or aspect with another without taking into account the whole context in which the relevant item appears. In the present case, the respondent contends that it is wrong merely to compare the length of hair provisions regarding male and female prisoners. It is important, the respondent says, to have regard to the whole context, this being custodial discipline in prisons.[34] Put another way – and I would have no quarrel with this on a general level – it is important to examine what is complained about as discrimination in context. After all, the comparison exercise between the complainant and the compared person must, as stated before, be a comparison between like and like. Section 10 of the SDO states that relevant circumstances must be taken into account. This taking into account of the whole is what is involved in the so‑called package approach. 26. This term finds its origin, certainly its articulation, in Smith v Safeway PLC.[35] The case concerned a complainant who was an assistant in the delicatessen department of a well‑known supermarket. He was dismissed on account of his refusal to cut his hair; his employers had a dress and appearance code which required male, but not female, staff to have hair not below collar length. The complainant claimed compensation against the employers on the basis of sex discrimination. On appeal from the Employment Appeal Tribunal, the Court of Appeal held against the complainant on the basis that it was necessary to look at the matter in proper context and the context of that case was a dress and appearance code. Accordingly, in this context there had to be adopted a package approach whereby it was accepted that men and women were not necessarily to be treated identically. Phillips LJ said this:-[36] “In my judgment, a package approach to the effect of an appearance code necessarily follows once one accepts that the code is not required to make provisions which apply identically to men and women. Phillips J. held that this was the approach more likely to lead to a sensible result in that case and in cases like it. I agree. This is not to say that when applying the test, the requirement of one particular item of a code may not of itself have the effect that the code treats one sex less favourably than the other. But one has to consider the effect of any such item in the overall context of the code as a whole. Mr Bibby submits that if such an approach is legitimate, it must be confined to dress and cannot be extended to hair. He makes the particular point that employees only have to comply with requirements as to dress while they are in the workplace, but can change their clothes so as to dress as they please once they leave work. As to this I accept Mr Elias’s argument that, while this may be a relevant consideration when applying the appropriate test, it does not affect the test itself. Appearance depends in part on ephemera, clothes, rings and jewellery worn, but it depends also on more permanent characteristics, tattoos, hair style, hair colouring and hair length. The approach adopted in the Schmidt case can, in my judgment, properly be applied to both types of characteristic.” The reference to the Schmidt case is a reference to Schmidt v Austicks Bookshops Ltd,[37] in which the Employment Appeal Tribunal also approached the matter on a broader basis, rather than using an item by item comparison. There, the alleged discrimination consisted of female employees not being permitted to wear trousers. 27. The respondent points to a number of cases, all involving dress or appearance codes, to demonstrate that the package approach has been commonly applied. Thus, for example, the requirement to wear a uniform for nurses did not mean that male and female nurses had to be treated identically.[38] 28. It is important of course to reiterate that the package approach ought to be treated as an exercise in putting matters in proper context, applying some common sense as well, so as to enable a proper comparison to be made for the purpose ultimately of discovering whether or not less favourable treatment has been accorded to the complainant in the particular aspect about which he or she has complained as being discriminatory. To take another example, where an appearance code required employees “to present a clean and tidy appearance and to dress in a businesslike way”, it was held[39] that a male employee who was required to wear a collared shirt and tie at work (whereas female employees were not) did not necessarily mean there was less favourable treatment. Keith J, who chaired the Employment Appeal Tribunal in the case, referred to the need to look at context and then continued:-[40] “Thus, an even‑handed approach does not necessarily mean that members of one sex are treated less favourably than members of the other simply because members of one sex are required to wear clothing of a particular kind but members of the other are not. It will depend on ‘the overall context of the code as a whole’. The relevant context when considering the code introduced by Jobcentre Plus was its overarching requirement for its staff to dress in a professional and businesslike way. The issue which the employment tribunal should have addressed, therefore, was whether the requirement for male members of staff to wear a collar and tie whereas no particular form of dress was required for female members of staff meant that the male members of staff were being treated less favourably than female members of staff in the context of that overarching requirement which applied to all members of staff. We do not think that the employment tribunal addressed that issue.” I would add here that one would almost invariably need to look at the objectives of the code, or underlying policy or reason in question in order to picture the whole context. 29. However, care needs to be taken when adopting the package approach to ensure that it does not become an exercise of merely comparing features applicable to the complainant with separate features belonging to the compared person and then asking whether overall, the two persons have been treated equally. The approach in discrimination cases is not a “tit for tat” or “swings and roundabouts” approach. As has been said,[41] “In deciding whether a woman who is prevented from wearing trousers to work is being less favourably treated on the ground of her sex than a comparable man, courts and tribunals should be wary of arguments which seek to balance the fact that a woman is denied opportunity X with the fact that men are denied opportunity Y”. This passage was referred to in the article by Robert Wintenute Recognising New Kinds of Direct Sex Discrimination: Transsexualism, Sexual Orientation and Dress Codes[42] who says this: “Sex distinctions applying to different choices cannot be lumped together and their net effect examined. Courts must look instead at their effect on the ability of individuals to make each specific choice. For the woman who wants badminton at the same price as a man, free swimming is no consolation. For the man who wants to wear a pony‑tail or a skirt, it is no consolation that women are prohibited from wearing short hair or trousers.” It is always necessary to examine whether the particular act or policy said to be discriminatory does in context result in less favourable treatment. Moreover, sometimes it may be that the particular act or policy, even though part of a whole, treats the complainant less favourably to such an extent that it would have the effect of rendering the whole policy as being discriminatory: see Smith v Safeway PLC.[43] 30. It is again unnecessary to define the limits of the package approach. Apart from anything else, much depends on the facts of any given case. I also add this. The way that past cases have been dealt with on their facts, provides no sure indication that seemingly similar factual situations will nowadays still produce the same outcome. 31. One final point on packaging. In some of the cases,[44] the approach has been to examine the aspect of less favourable treatment by reference to convention or conventional standards. I have touched upon this earlier.[45] In Smith v Safeway PLC, Phillips LJ stated[46] that a dress code was not rendered discriminatory if it “applies a standard of what is conventional”. 32. What may constitute convention or conventional standards will vary depending on the context and facts of any given case. For example, in a dress code which has its objective dressing in a businesslike way,[47] there may be conventional standards in this context which differ from how people may dress in everyday, social contexts. On the assumption this factor is relevant in the first place, what is required, however, is some factual basis to support what is asserted to be convention or conventional standards. A mere assertion or subjective belief without more will be unlikely to overcome the evidential hurdle. 33. What if asserted conventions or conventional standards involve stereotyping? It is to this facet I now turn. B.7 Stereotyping 34. Generally speaking, there will be found discriminatory conduct if there has been stereotyping. Stereotyping occurs when an individual or a group is treated in a different way to others in the same position by reason of a stereotype that has been applied to that individual or group. In the Roma case,[48] the claimants in that case, travelling from the Czech Republic to the United Kingdom, were subject to much tighter, longer and more intrusive immigration questioning than others simply because they were Roma (that is of Romani ethnic origin). They complained of less favourable treatment being accorded to them on the basis of their race. Even though there was some evidence to suggest that Roma persons had in the past advanced false claims to enter the United Kingdom, it was held by the House of Lords to be unacceptable to apply stereotypes. Baroness Hale of Richmond said this:[49] “The person may be acting on belief or assumptions about members of the sex or racial group involved which are often true and which if true would provide a good reason for the less favourable treatment in question. But ‘what may be true of a group may not be true of a significant number of individuals within that group’: see Hartmann J in Equal Opportunities Commission v Director of Education[50] …. The object of the legislation is to ensure that each person is treated as an individual and not assumed to be like other members of the group.” 35. Equal Opportunities Commission v Director of Education provides another example of discrimination by stereotyping, this time on account of sex. That was a case in which the Government’s then education policy of entry from primary school to secondary school was found to be discriminatory against girls purely on the assumption that at the relevant age, girls were more academically developed than boys.[51] 36. Where reliance is placed on convention or conventional standards, but they reflect stereotyping, a question may arise as to the appropriateness of relying on such convention or conventional standards for the purpose of defeating an argument of less favourable treatment. This is the point made by the author in Sex Discrimination Law[52] in criticising the Schmidt case: “Is an employer’s policy of refusing women to wear trousers to work sex discrimination under the 1975 Act?[53] The EAT decision in Schmidt, validating such policy if analogous, albeit different, restrictions are imposed on men, is not convincing. That an employer is requiring men to do what they normally do – wear trousers – and asking women to do what they normally do – wear skirts – cannot, of itself, amount to a non‑discriminatory policy. Otherwise employers would always have a defence if their practices mirrored social behaviour. This would clearly conflict with a major objective of the 1975 Act, which was introduced precisely because aspects of social behaviour were unfair to women”. 37. As will be seen later, it is unnecessary on the facts of the present case to resolve some of the potential difficulties, especially in the context of convention or conventional standards, that can arise in relation to stereotyping. This should be left to a case in which the point properly arises. It suffices to say that the point is capable of many nuanced arguments, and is certainly not without difficulty both conceptually and as applied in practice. B.8 The difference in treatment on the basis of sex 38. This is the 4th requirement stated in para 15(4) above. It is the crucial question. As Lord Nicholls of Birkenhead said in Nagarajan v London Regional Transport,[54] “Thus, in every case it is necessary to inquire why the complainant received less favourable treatment. This is the crucial question.” However, in asking the question “why?”, it is important to distinguish finding out what caused the alleged discriminatory treatment in question (this is permissible, indeed critical) from looking at justification or motive (this is not permissible).[55] It is also an inquiry based on substance and not form. In James v Eastleigh Borough Council,[56] the plaintiff complained of discrimination in a leisure centre operated by the defendant council in which free admittance was available only to those persons who had reached pensionable age. The plaintiff and his wife were both 61 years of age. While his wife gained entrance free of charge, the plaintiff was charged admission. The pensionable age for women was 60, for men it was 65. In the Court of Appeal, it had been held that the less favourable treatment given to the plaintiff was not on the basis of sex but on the basis of pensionable age, a criterion that applied equally to men and women. The majority of the House of Lords[57] held otherwise and analysed the problem as a matter of substance. Lord Bridge of Harwich, with whose speech Lord Ackner and Lord Goff of Chieveley agreed, said of the approach of the Court of Appeal:[58] “The fallacy, with all respect, which underlines and vitiates this reasoning is a failure to recognise that the statutory pensionable age, being fixed at 60 for women and 65 for men, is itself a criterion which directly discriminates between men and women in that it treats women more favourably than men ‘on the ground of their sex’”. 39. The above being the applicable legal approach, I now turn to its application to the facts. C. APPLICATION TO FACTS 40. There is no controversy between the parties regarding the requirements in paras 15(1) and (4) above: the respondent accepts there is a difference in the treatment between male and female prisoners, and that this difference is on the basis of sex. Further, as I understand it, there is no real controversy regarding the para 15(2) requirement either: it is accepted that male and female prisoners are, for the purposes of hair length, in comparable positions. The real difference dividing the parties has been over the factor whether less favourable treatment, seen in proper context, has been accorded to male prisoners like the appellant, para 15(3) above.[59] Here, it should first be noted that on its face, without more, SO 41‑05 suggests that male prisoners are not only treated differently to female prisoners but are also, on account of the absence of choice, treated less favourably. The burden is then passed onto the respondent to say why this is not so. 41. The respondent’s approach has been inconsistent in the lower courts. Before Au J, it was the respondent’s case “that SO 41-05 is a preventive operational measure which has the effect of reducing the number of risks which threaten the individual rights of prisoners while in custody.”[60] The risks were enumerated as follows:-[61] “These risks are in summary (a) the inherent vulnerability of prisoners with long hair in the case of an attack by another inmate involving violence; (b) the risk that long hair is used as a potential method of concealing prohibited items (eg, a razor blade or self-made weapons) which could be used by a prisoner both to attack other inmates, to inflict self-harm, or for suicide; (c) the risk of violence associated with triad or gang affiliation; and (d) the risk of prisoners using long hair as a readily accessible tool (as opposed to a method of concealment) for self-harm and suicide. Importantly, it is the Commissioner’s evidence that, from experience (partly backed by some statistics), these risks are significantly higher in the male inmates population than the female inmates population. It is therefore the Commissioner’s position that the real ground for the hair cutting requirement is not on the sex but on the maintenance of prison security and discipline.” Although this passage indicates that the respondent’s position was that it was disputing whether the different treatment was on the ground of sex, it clearly was since the asserted difference lay in the contention that security risks were higher in the case of male prisoners than female. Be that as it may, the real argument of the respondent was that by reason of these enhanced risks, male prisoners had to be treated differently, but they did not receive less favourable treatment. The respondent seemed also to be arguing that the relevant circumstances between male and female prisoners were not alike.[62] 42. Au J held against the respondent on the basis of stereotyping[63] in that the various risks involved stereotypes of male prisoners “as a gender as a whole”. Whether or not this analysis is sound in the context of security risks is immaterial because there is a more fundamental objection. The evidence adduced by the respondent in the proceedings to prove the existence of the said risks does not demonstrate any real link between the length of a prisoner’s hair and the asserted risks. The evidence is contained in the affirmation of Leung Kam Yan[64] dealing with the aspect of security concerns.[65] Although certain statistics are given, nowhere is it compellingly explained, other than by way of conjecture, why there is a link between these concerns and the length of hair. Ultimately, the respondent’s evidence does not prove or explain (as distinct from merely assert) why male and female prisoners should be treated differently in the context of security concerns relating to the length of hair. 43. The respondent’s stance shifted substantially in the Court of Appeal. The emphasis was instead placed on custodial discipline. His position, accepted by Lam VP (who gave the main judgment), was this: “[T]he common underlying objective of the policy in issue is to foster custodial discipline by imposing reasonable uniformity and conformity among the inmates (both male and female inmates) and reasonable restrictions are set by reference to the respective conventional standards for appearance for male and female inmates.”[66] The reference to conventional standards was a reference to “the conventional standards of appearance for men and women in our society”.[67] The conventional standards, according to the Court of Appeal, amounted to these: “The conventional hairstyle of male persons in Hong Kong is a short hairstyle, male inmates are therefore required to wear a similar short hairstyle. On the other hand, as the conventional hairstyle of Hong Kong women is that it may either be long or short (putting the matter in a simplified way), female inmates are therefore allowed under the female haircut requirement to keep their own hairstyles.”[68] 44. The respondent maintains this position before us and argues essentially that in the context of custodial discipline, there is no less favourable treatment given to male prisoners compared with female prisoners. As stated above, the respondent contends that he is entitled, as part of custodial discipline, to impose reasonable uniformity and conformity in appearance among inmates, whether male or female.[69] In the present case, the respondent has done so by reference to SO 41‑05, notwithstanding that that standing order deals only with health and cleanliness at least as far as male prisoners are concerned. 45. The respondent’s position is contained in the affirmation of Supt Leung:- “5. It is part of the CSD’s overall mission and objectives to provide a secure, safe, humane, decent and healthy environment for people in custody. In order to achieve the mission, maintaining prison security and custodial discipline are of paramount importance whereas preserving health and cleanliness (including the requirement for male prisoners to have reasonably uniform haircut), amongst numerous stipulations and orders, is only one of the requirements under the regime within prison context for the purpose of maintaining prison security and custodial discipline. Custodial Discipline Concerns 6. The CSD considers that a fundamental part of custodial discipline is reasonable uniformity within correctional facilities. Custodial discipline ensures proper administration of correctional facilities by implementing uniform rules on all matters for the inmate population. Within a prison context, reasonable uniformity is important because it fosters both a sense of collective conformity and respect for prison authority among inmates during their remedial terms. As a matter of proper administration in an environment that is meant, in part, to instill law‑abiding concepts and to correct past behavior, individuality is de‑emphasized to give way to custodial discipline. 7. Custodial discipline is enforced by a set of Standing Orders issued by the Commissioner. The Standing Orders cover a variety of matters including, but are not limited to: diet, clothing, work hours, exercise routine, sleep hours, as well as hair cutting (SO 41‑05) for reasonable uniformity and maintaining custodial discipline. The Commissioner has general authority under Prison Rule 77 to make such standing orders which are subject to review semi‑annually. Therefore, while SO 41‑05 can be said to be authorized under Prison Rules 34 and 119, it is also authorized under Prison Rule 77 as part of the Commissioner’s general powers of custodial administration to maintain custodial discipline in all correctional facilities.” 46. As pointed out earlier, SO 41‑05 prescribes different treatment for male and female prisoners. The respondent seeks to explain this difference in treatment by reference to the underlying conventional standards of appearance in society for men and women. So analysed, it is argued it cannot be said that there is any less favourable treatment as far as male prisoners are concerned because the length of hair requirements contained in the standing order treat men and women in accordance with conventional standards. Accordingly, whether one adopts the item by item approach (simply comparing hair length requirements) or the package approach (this is said to be the need for uniformity and conformity in appearance as a matter of custodial discipline), the respondent contends that the appellant has simply not made out a case of less favourable treatment.[70] 47. I am unable to accept these submissions. 48. It can of course be readily accepted that custodial discipline is a legitimate factor to be considered, as can the proposition that a person can expect to be deprived of certain privileges or freedoms normally enjoyed outside of incarceration. But we are considering and comparing the respective situations of male and female prisoners in determining the issue of discrimination. It is necessary not to lose focus of this. SO 41‑05 clearly sets out a different treatment for male and female prisoners. 49. The stated objective, policy or reason for the difference in treatment being custodial discipline as earlier set out,[71] the next step is to analyse the difference in treatment by reference to it. For my part, it is difficult to see how a difference in treatment regarding the length of hair between male and female prisoners based on asserted conventional standards has any reasonable connection with custodial discipline. The reliance on conventional standards amounts to no more than saying[72] that the respondent wished, as a matter of custodial discipline, to have inmates in prison have the same length of hair as persons outside of prison. It is not readily apparent, and no explanation was provided by the respondent, as to why this had any reasonable connection with custodial discipline. Mr Wong emphasised the point that in prison, there has to be a de‑emphasis on a prisoner’s individuality. As Supt Leung said in his affirmation,[73] “individuality is de‑emphasized to give way to custodial discipline”. This point can perhaps as a general statement be accepted but in the present case, it is difficult to accept, without a proper explanation, why individual choice should be denied to male prisoners but not female ones, and what this selective denial of choice has to do with a de‑emphasis on individuality anyway. 50. Without a reasonable connection to the stated objective, policy or reason, the respondent does not really begin to explain the difference in treatment and why there has not been less favourable treatment. 51. There is a further impediment to the respondent’s argument. The respondent’s submissions depend on the factual premise that there exist conventional standards of appearance for men and women in society in relation to the length of hair. The respondent refers to these standards in implementing the policy on hair lengths required by SO 41‑05. Does the evidence support this contention? Throughout the respondent’s submissions, there are references to the evidence in support being unchallenged. However, the evidence far from establishes this and it is difficult to accept the evidence at face value. The respondent relies on[74] para 36 of the affirmation of Supt Leung:- “Finally, I would like to point out that it is not factually correct to say that female inmates do not have any hair restrictions. For example, in Lo Wu Correctional Institution, female inmates with long hair are required to tie back their hair in accordance to hairstyle requirement issued by the institution. Attached and shown to me is a copy of the “Hairstyle Requirement of Male and Female Prisoners”, which shows the photos of required standard of hairstyle in Stanley Prison and Lo Wu Correctional Institution, marked as Exhibit “LKY-17”. The hairstyle requirements for both male and female prisoners are specified by making reference to the hairstyle of male and female persons in Hong Kong society without carrying any stigmatization. It is not as if male prisoners are required to shave off all their hair, they simply must keep their hair about the length of a standard hair cut. Such length is objectively reasonable and does not impose an undue burden upon prisoners, whose rights and privileges are more limited as a result of lawful incarceration.” (Emphasis added) 52. It may be that what was said in this paragraph was not challenged by the appellant as such but its contents do not provide a sufficient factual basis for the conventional standards relied on by the respondent. First, SO 41‑05 refers on its face to “health and cleanliness”. No explanation is provided as to how these aspects are related to conventional standards for hair length and it is difficult to see how they can. The respondent has simply used it as a reference point. Secondly, this passage from Supt Leung’s affirmation does not mention conventional standards as such although admittedly reference was made to the hairstyle of men and women in Hong Kong society. Thirdly and most important, no details are provided and no basis is given for saying that in our society, the conventional hairstyle for men is a short one whereas for women, hair can be long or short.[75] There must be sufficient evidence going to these matters; they cannot simply be asserted. In his submissions to us, Mr Wong seemed to suggest it was sufficient for Supt Leung merely to state this fact as though it was some sort of factual finding on his part and that it was for the appellant to disprove it. The old adage of “he who asserts, must prove” applies. It is for the respondent to prove the conventional standards he relies on. Moreover, these are not matters of which judicial notice can be taken. On the contrary, one would have thought judicial notice would be taken, if anything, of the fact that the hairstyles for men and women in our society would be quite diverse. Mr Wong sought to reinforce his submissions by referring to the fact that SO 41‑05 had been subject to semi‑annual reviews since its introduction (in the mid‑1950s we are told). If this were so, it seems somewhat unrealistic, if not bizarre, to suggest that SO 41‑05, if it was intended to reflect conventional standards in hair length in society, had not been amended in any way since that time. Fourthly, there is some inconsistency in the way the Court of Appeal treated the aspect of conventional standards. Its view (as stated above) as to the conventional standards for hair length for men and women is to be contrasted with the reference later in its judgment to there being “different conventional standards for appearance in our society.”[76] 53. It is unnecessary to deal with the further point raised by the appellant[77] as to whether in any event, conventional standards regarding the length of men and women’s hair in society involved stereotyping. Apart from anything else, until one knows the exact extent of the evidence regarding this, one is not in a position to embark on a meaningful analysis. As just discussed, the respondent’s evidence is unsatisfactory and such conventional standards are not made out. Accordingly, without such evidence, in the present case one is simply left with his view, based on SO 41-05, of what hair lengths for men and women ought to be in society, and this amounts to stereotyping on the respondent’s part. 54. For these reasons, I am of the view that less favourable treatment was given to the appellant compared with female prisoners. Accordingly, all four requirements as stated in para 15 above are satisfied in the present case for the purposes of the SDO. There has been discrimination on the basis of sex. 55. I should finally in the discussion in the present section just make this point. The respondent has the responsibility for and expertise in administering prisons. His duties are set out in the Prisons Ordinance. In this respect, he should be given a wide margin of discretion to adopt appropriate policies. However, he must do so consistently with applicable laws and, on the facts of the present case, he has discriminated against the appellant in violation of s 5(1)(a) of the SDO. D. THE CONSTITUTIONAL ISSUE UNDER ARTICLE 25 OF THE BASIC LAW 56. In view of the conclusion reached on the previous issue, it is unnecessary to deal with this issue. However, on the facts of the present case, the outcome would not be different under Article 25 of the Basic Law. E. CONCLUSION 57. For the above reasons, the appeal is allowed. As to the exact form of the order, the respondent asked that the Court should entertain further submissions in the event the appeal was to be allowed. I would therefore order that submissions on the form of order and on costs be made in writing. I would direct that the respondent file and serve submissions within 14 days of the handing down of this judgment. The appellant will have 14 days from being served with the respondent’s submissions to file and serve submissions in reply. The respondent will have 7 days from being served to file and serve any submissions in reply. Mr Justice Ribeiro PJ: 58. I agree with the judgment of the Chief Justice. Mr Justice Fok PJ: 59. I agree with the judgment of the Chief Justice. Mr Justice Chan NPJ: 60. I agree with the judgment of the Chief Justice. Lord Collins of Mapesbury NPJ: 61. I agree with the judgment of the Chief Justice. Mr Hectar Pun SC, Ms Annie Leung and Mr Anson Wong Yu Yat, instructed by Ho Tse Wai & Partners, assigned by the Director of Legal Aid, for the Appellant Mr Stewart Wong SC, Mr Jin Pao SC and Mr John Leung, instructed by the Department of Justice, for the Respondent [1] Cap 480 (“the SDO”). We are concerned in particular with section 5(1)(a) of that Ordinance (set out in para 10 below). [2] Article 25 states that “All Hong Kong residents shall be equal before the law”. [3] As set out in the Hong Kong Bill of Rights Ordinance Cap 383 (“the HKBORO”). This article incorporates under Hong Kong law the provisions of the International Covenant on Civil and Political Rights (see Article 39 of the Basic Law). [4] Issued by the Commissioner of Correctional Services pursuant to Rule 77(4) of the Prison Rules Cap 234A under the Prisons Ordinance Cap 234. Further, the reference in the Standing Order to health and cleanliness can be traced to Rules 34 and 119 of the Prison Rules. These provide as follows:- (1) Rule 34 “34. Obedience to directions as to cleanliness Every prisoner shall obey such directions as regards washing, bathing, shaving and hair cutting as may from time to time be prescribed.” (2) Rule 119 “119. Duty as to personal cleanliness of prisoners The Chief Officer shall ensure that the prisoners’ clothing is kept in good state of repair, their hair kept trimmed, and their washing, hair clipping and personal ablutions attended to.” [5] In a judgment dated 17 January 2017 (“CFI Judgment”). [6] Cheung CJHC, Lam VP and Poon JA in a judgment dated 30 April 2018 (“CA Judgment”). [7] In a judgment dated 22 January 2019. [8] Ma CJ, Fok PJ and Chan NPJ. [9] (2018) 21 HKCFAR 324, at para 33. [10] [2009] UKSC 15, [2010] 2 AC 728, at para 56 (per Baroness Hale of Richmond JSC). [11] In the Court of Appeal, Cheung CJHC dealt with the appeal also on the basis of indirect discrimination, but this has not been pursued before us. [12] (2000) 3 HKCFAR 459, at 476A-D. [13] [1989] 1 AC 1155, at 1194A-B. [14] Section 1(1) of the Sex Discrimination Act 1975 has the same wording as s 5(1) of the SDO. [15] [1990] 2 AC 751, at 765D. [16] [2004] UKHL 55, [2005] 2 AC 1, at para 73. [17] See JFS, at para 56 quoted in para 11 above. [18] [2005] UKHL 37, [2006] 1 AC 173, at para 49 (in a passage quoted by the Court in QT v Director of Immigration (2018) 21 HKCFAR 324, at para 27). [19] Birmingham City Council v Equal Opportunities Commission: see para 14 fn 13 above; Equal Opportunities Commission v Director of Education [2001] 2 HKLRD 690. [20] At 1176B-C. [21] At 1193G-H. [22] At 765D (Lord Bridge of Harwich). [23] At paras 16, 22, 23 (per Lord Phillips of Worth Matravers PSC). [24] [2008] NIQB 21, at para 21. [25] See Section B.6 below. [26] See JFS, at paras 14, 17, 20, 22, 57, 59, 113, 115, 116, 132 and 141. [27] At para 116. [28] [2013] EWHC 687 (Admin). [29] At para 64. It is interesting to note that the consideration of “privacy and decency” features in the SDO in relation to communal accommodation: see s 52(1). [30] [1993] 2 SCR 872. [31] The equality provision of the Charter. [32] At 877. [33] The respondent is represented in this appeal by Mr Stewart Wong SC, Mr Jin Pao SC and Mr John Leung. [34] This, after all, is expressly referred to in s 9 of the Hong Kong Bill of Rights Ordinance: see para 2 above. [35] [1996] ICR 868. [36] At 877C-F. [37] [1978] ICR 85. [38] See Burrett v West Birmingham Health Authority [1994] IRLR 7. [39] In Department for Work and Pensions v Thompson [2004] IRLR 348. [40] At para 27. [41] David Pannick: Sex Discrimination Law (1985) at Pg 187. [42] (1997) 60 MLR 334, 355. [43] At 877C-D, see para 26 above. [44] See for example Re McMillen at para 22 (“a code applying conventional appearance is not of itself discriminatory”); G v The Head Teacher and Governors of St Gregory’s Catholic Science College [2011] EWHC 1452 (Admin), at para 56 (“What is to be regarded as conventional may well vary as time goes by and will depend on the facts of a particular case”) and para 59 (“Furthermore, although cornrows for boys are by no means unusual, I am not persuaded that the defendants are wrong to regard them as not being conventional.”). [45] Paras 22 and 23 above. [46] At 877H – 878A. [47] Such as in Thompson. [48] Para 15 fn 16 above. [49] At para 82. [50] See para 18 fn 19 above. [51] The policy effectively boosted the academic scores of boys and in turn downgraded those of girls in primary schools such that boys then stood a better chance of gaining entry into the secondary school of their choice. [52] See para 29 fn 41 above, at Pg 187. [53] The Sex Discrimination Act 1975 which corresponds in material respects with the SDO. [54] [2000] 1 AC 501, at 510H-511A. [55] Para 20 above; see also JFS at para 64 (per Baroness Hale of Richmond JSC). [56] See para 14 fn 15 above. [57] The decision was a 3:2 one. The dissenting speeches of Lord Griffiths and Lord Lowry largely adopted the analysis of the Court of Appeal that it was pensionable age, and not sex, that led to the difference in treatment. [58] At 763H. [59] See Respondent’s written Case, at para 12(1). [60] Para 27 CFI Judgment. [61] Para 28 CFI Judgment. [62] The factor mentioned in para 15(2) above. [63] Para 40 CFI Judgment. [64] A superintendent of the Penal Administration Section, Operations Division of the Correctional Services Department. [65] See paras 9 to 20 of the affirmation. [66] At para 52 CA Judgment. [67] At para 66 CA Judgment (Lam VP); see also para 17 CA Judgment (Cheung CJHC). [68] Para 9 CA Judgment. [69] Rule 77(4) of the Prison Rules refers to the power of the respondent to issue orders for the discipline of persons. And, as stated earlier, s 9 of the Hong Kong Bill of Rights Ordinance refers also to “custodial discipline”. [70] I have condensed the respondent’s submissions which are largely to be found in paras 4 to 7, 27 to 65 of his written Case. [71] Paras 21, 43 to 45 above. [72] This was confirmed by Mr Wong in argument. [73] See para 45 above. [74] In para 6 of the respondent’s written Case. [75] See para 43 above. [76] See para 75 CA Judgment, in the context of stereotyping. [77] The appellant is represented by Mr Hectar Pun SC, Ms Annie Leung and Mr Anson Wong.