An Appeal Court case opened this week into whether the entry policy of Britain’s largest Orthodox school breaches anti-discrimination laws.

It has been brought on behalf of “M”, a boy who was refused a place by JFS in London for September 2007 because his mother was converted by a non-Orthodox rabbi and therefore considered not Jewish by the school’s religious authority, the Chief Rabbi.

Lawyers for the boy maintain that to decide entry on the basis of whether a child’s mother is Jewish or not is racially discriminatory.

But at a High court judicial review last year, Mr Justice Munby upheld the school’s entry policy, saying it was based on religious, not racial, grounds.

M’s mother was an Italian Catholic who converted under Progressive auspices in the UK before her marriage to a Jewish man. The couple divorced, but M and his father are now active in a Masorti community in London.

Dinah Rose QC, acting for M’s father, told the Appeal Court that the case was not about the “vexed question” of who is a Jew. She said: “We accept that the Office of the Chief Rabbi has a right to determine under Jewish law, by whatever test it chooses, who it does or does not accept as a Jew.”

But school governors, she said, were “not free to adopt as the principal criterion for deciding who is awarded a place in a school, a test which is based on ethnic origin. Such a test may not be used by a school in its admission policy.”

To use matrilineal descent as an entry test — rather than religious belief or practice — discriminated against children whose mothers were not born Jewish, she argued.

Converts were also unfairly treated because their religious observance could be examined by the school’s rabbinical authorities, whereas that was not the case with applicants “whose mothers are of Jewish lineage”.

Ms Rose argued that even if the school thought the entry policy religiously motivated, it was “race-tainted” in the eyes of the law.

Clive Lewis QC, for the Schools’ Adjudicator (who deals with complaints over admissions policy), argued that Mr Justice Munby had been correct.

He added that any challenge to the admission rules for this year’s intake would be merely academic, as the places at the school have already been allocated and filled.

The Office of the Chief Rabbi is being represented by Lord Pannick, one of seven counsel for the hearing, due to have ended yesterday. They include lawyers for the government, which is defending the freedom of state-aided faith schools to determine their entry rules.

A US spokesman said: “The US has had to defend this appeal in order to ensure the future of our schools and community. The appeal cost is £50K-60K.