The case involved the admissions policy of JFS school, a state secondary school that has been educating Jewish children in London since 1732. M’s father, wanted M to go to the school: but he wasn’t given a place because according to Orthodox Jewish principles, M is not recognised as Jewish because his mother was not herself Jewish according to those rules. In Jewish Law descent is matriineal ie through the mother. M could become an Orthodox Jew when he came of age and personally chose his religion but until then he was fixed with the religion of his parents which may have been Jewish but was clearly not Orthodox Jewish
M's mother is Italian and was originally a Catholic who converted to Judaism under the auspices of a Non Orthodox Liberal synagogue but Orthodox Jews did not recognise her conversion. M's father claimed racial discrimination, on the basis that his son was turned down because of his mother’s non-Jewish ethnic origins.
The Court split 5-4 on the main issue: the majority holding that the admissions policy amounts to direct discrimination on racial grounds.
Lady Hale said in para. 66
Is the criterion adopted by the Chief Rabbi, and thus without question by the school, based upon the child’s ethnic origins? In my view, it clearly is. M was rejected because of his mother’s ethnic origins, which were Italian and Roman Catholic. The fact that the Office of the Chief Rabbi would have over-looked his mother’s Italian origins, had she converted to Judaism in a procedure which they would recognise, makes no difference to this fundamental fact. M was rejected, not because of who he is, but because of who his mother is. That in itself is not enough. If M had been rejected because his mother shopped in Waitrose rather than Marks and Spencer, that would not have been because of her or his ethnicity. But it was because his mother was not descended in the matrilineal line from the original Jewish people that he was rejected. This was because of his lack of descent from a particular ethnic group.
Lord Mance said in para. 86:
Some other Jewish denominations, the Court was told, have other tests, e.g. looking, or looking also, at the patrilineal line. But all such tests look, in one way or another, at ethnic origins…. This case cannot therefore be viewed as a mere disagreement between different Jewish denominations, for example about the criteria for conversion. It turns, more fundamentally, on whether it is permissible for any school to treat one child less favourably than another because the child does not have whatever ancestry is required, in the school’s view, to make the child Jewish.
All of these rulings can be regarded as sound on a merely technical level but leads to a result which Lord Rodger’s describes in para. 226 as extraordinary.
The majority’s decision leads to such extraordinary results, and produces such manifest discrimination against Jewish schools in comparison with other faith schools, that one can’t help feeling that something has gone wrong.
He went on in para 228
Lady Hale says that M was rejected because of his mother’s ethnic origins which were Italian and Roman Catholic. I respectfully disagree. His mother could have been as Italian in origin as Sophia Loren and as Roman Catholic as the Pope for all that the governors cared: the only thing that mattered was that she had not converted to Judaism under Orthodox auspices. It was her resulting non-Jewish religious status in the Chief Rabbi’s eyes, not the fact that her ethnic origins were Italian and Roman Catholic, which meant that M was not considered for admission. The governors automatically rejected M because he was descended from a woman whose religious status as a Jew was not recognised by the Orthodox Chief Rabbi; they did not reject him because he was descended from a woman whose ethnic origins were Italian and Roman Catholic.
and at para. 230
Even supposing that the governors knew about his origins, they were quite irrelevant and played no part in their decision. The governors were simply asked to consider admitting him as the son of a Jewish mother. They declined to do so because his mother had not converted under Orthodox auspices. It was her non-Orthodox conversion that was crucial. In other words, the only ground for treating M less favourably than the comparator is the difference in their respective mothers’ conversions – a religious, not a racial, ground.
In Para 233 he goes on
The aim of the School, to instil Jewish values into children who are Jewish in the eyes of Orthodoxy, is legitimate. And, from the standpoint of an Orthodox school, instilling Jewish values into children whom Orthodoxy does not regard as Jewish, at the expense of children whom Orthodoxy does regard as Jewish, would make no sense. That is plainly why the School’s oversubscription policy allows only for the admission of children recognised as Jewish by the Office of the Chief Rabbi. I cannot see how a court could hold that this policy is a disproportionate means of achieving the School’s legitimate aim
Lord Brown agrees at para para. 255 quoted Munby J in the High Court case of E v JFS (Jewish Free School)  EWHC 1535/1536 (Admin)
Adopting some alternative admissions policy based on such factors as adherence or commitment to Judaism (even assuming that such a concept has any meaning for this purpose in Jewish religious law) would not be a means of achieving JFS’s aims and objectives; on the contrary it would produce a different school ethos. If JFS’s existing aims and objectives are legitimate, as they are, then a policy of giving preference to children who are Jewish applying Orthodox Jewish principles is, they say, necessary and proportionate – indeed, as it seems to me, essential – to achieve those aims . . . JFS exists as a school for Orthodox Jews. If it is to remain a school for Orthodox Jews it must retain its existing admissions policy; if it does not, it will cease to be a school for Orthodox Jews. Precisely. To this argument there is, and can be, no satisfactory answer.As we Lawyers put it "I respectfully agree" because he recognised that the decision of the Court produced an absurdity and the Law should not do that certainly not the law as propounded by a Supreme Court