"The scheme of the Act is that a rebuttable presumption of sex discrimination arises once the gender based comparison shows that a woman doing like work or work rated as equivalent or work of equal value to that of a man, is being paid or treated less favourably than the man. The variation between her contract and the man's contract is presumed to be due to the difference of sex. The burden passes to the employer to show that the explanation for the variation is not tainted with sex. In order to discharge this burden the employer must satisfy the tribunal on several matters. First, that the preferred explanation, or reason, is genuine, and not a sham or pretence. Second, that the less favourable treatment is due to this reason. The factor relied upon must be the cause of the disparity. In this regard, and in this sense, the factor must be a "material" factor, that is, a significant and relevant factor. Third, that the reason is not "the difference of sex"
"14. However, it is clear from the case law of the court that the onus may shift when that is necessary to avoid depriving workers who appear to be the victims of discrimination of any effective means of enforcing the principal of equal pay. Accordingly, when a measure distinguishing between employees on the basis of their hours of work has in practice an adverse impact on substantially more members of one or other sex, that measure must be regarded as contrary to the objective pursued by article 119 of the Treaty unless the employer shows that it is based on objectively justified factors unrelated to any discrimination on grounds of sex …Similarly, where an undertaking applies a system of pay which is wholly lacking in transparency, it is for the employer to prove that his practice in the matter of wages is not discriminatory, if a female worker establishes, in relation to a relatively large number of employees, that the average pay for women is less than that for men … 15. In this case, as both the health authority and the United Kingdom observe, the circumstances are not exactly the same as in the cases just mentioned. First, it is not a question of a de facto discrimination arising from a particular sort of arrangement such as may apply, for example, in the case of part-time workers. Secondly, there can be no complaint that the employer has applied a system of pay wholly lacking in transparency since the rates of pay of National Health Service Speech Therapist and Pharmacists are decided by regular collective bargaining processes in which there is no evidence of discrimination as regards either of those two professions. 16. However, if the pay of speech therapists is significantly lower than that of pharmacists and if the former are almost exclusively women while the latter are predominantly men, there is a prima facie case of sex discrimination, at least where the two jobs in question are of equal value and the statistics describing that situation are valid… 18. Where there is a prima facie case of discrimination, it is for the employer to show that there are objective reasons for the difference in pay."
"17. …In our view the appropriate question to ask when search for a requirement or condition is what one has to do to obtain the advantage enjoyed by the comparator group. In the present case the answer to that question is that one has to be a member of that comparator group. It is true that this answer does not, as is so often the case, raise a need to satisfy qualification for recruitment. The answer we have given refers simply to the existence of a fact situation. Those who are members of the group can satisfy the condition of obtaining the advantage; those who are not members of the group cannot satisfy that condition."
"…in order to establish whether it is contrary to article 119 of the Treaty and to Directive 75/117 for midwives to be paid less, the national code must verify whether the statistics available indicate that a considerably higher percentage of women than men work as midwives. If so, there is indirect sex discrimination unless the measuring point is justified by objective factors unrelated to any discrimination based on sex"
"…whether the statistics available indicate that a considerably smaller percentage of women than men is able to fulfil the requirement imposed by the statutory measure."
"…If a difference in pay between the two groups compared is found to exist, and if the available statistical data indicate that there is a substantially higher proportion of women than men in the disadvantaged group, article 119 of the Treaty requires the employer to justify the difference by objective factors unrelated to any discrimination on grounds of sex."
"…we agree with Mr Ford that Enderby cannot be understood as a case whose principle only applies in circumstances in which the disadvantaged group is made up "almost exclusively" of women. First, if that is the test what does "almost" mean? Enderby shows that it means 98% and Mr Lynch has conceded that it also means 94%. But would it cover 90% or 85%? What is the cut-off point, and what is the explanation for it? If it is, say, 85% what is the magic of the different between 84% and 86%? If Mr Lynch is correct in his submission as to the extent of the principle established by Enderby , then we consider that the principle would be too uncertain to be capable of practical application, if indeed it could be regarded as being a principle at all. We cannot accept that the Court of Justice was deciding the case on the narrow and unreasonable basis that Mr Lynch suggest. Secondly, and flowing from this, we consider that the broader underlying principle of Enderby must be, and is, that there will be cases in which, having regard to the relative sizes of the proportions of women in the disadvantaged group and men in the advantaged group, a prima facie case of direct sex discrimination in relation to pay will be regarded as arising that is sufficient to cast on to the employer the burden of proving that the pay difference is objectively justifiable. We consider that is the only rational basis upon which the decision can have been founded."
"…the National Court is essentially asking whether the inconvenient hour of supplement must be taken into consideration in calculating the salary used as the basis for a pay comparison for the purposes of article 119 of the Treaty and Directive 75/117."