The legal battle over entry to JFS will reach a climax next week when a three-day hearing begins at the new Supreme Court in London on Tuesday.

As many as nine of the 11 judges at the new court — which supersedes the House of Lords — are listed to hear the case, compared with the usual five for most cases.

The north London school, backed by the United Synagogue, will be trying to reverse a decision in June by the Court of Appeal that its entry policy was unlawful. The case originally came to the High Court the previous year on behalf of a boy refused entry to JFS because his mother’s non-Orthodox conversion was not recognised by the Office of the Chief Rabbi.

But the impact of the Appeal Court ruling — which the Chief Rabbi Sir Jonathan Sacks said in effect branded Judaism as “racist” — went far beyond JFS. It has forced many Jewish schools to revise their admissions polices for next September.

According to the Appeal Court, schools could no longer offer places on the basis of whether a parent was Jewish or not, because this amounted to racial discrimination.

JFS had argued that its entry policy complied with Jewish law and therefore was an issue of religion: under the law, religious schools can give priority to pupils on religious grounds.

But the Appeal Court said that since Jews are classified as an ethnic group under the Race Relations Act, using Jewish status to decide entry was a matter of ethnic origin, not belief, and so fell foul of race relations law.

As a result, Jewish schools have had to devise controversial new entry rules, asking parents to produce “certificates of practice” signed by rabbis or other officials to demonstrate a child’s synagogue attendance or other observance.

Next week’s hearing will again pit two of British Jewry’s finest legal brains against each other — Dinah Rose QC acting for the father of the boy, and Lord Pannick for JFS.

Besides the two main parties, the court has granted five other organisations the right to be “interveners” — enabling them to put submissions to the court: the United Synagogue, the Board of Deputies, the Equalities and Human Rights Commission, the Department of Children, Schools and Families, and the British Humanist Association.

The Board of Deputies will have its own QC in court, David Wolfson.

By coincidence, the opening of one of the most important legal cases in British Jewry history coincides with the introduction of the Chief Rabbi to the House of Lords, a few hundred yards away.

If the Supreme Court finds against JFS, one option being explored by community leaders is to propose an amendment to the Equality Bill going through Parliament which would allow Jewish schools to restore their old entry rules. And if that happens, the Chief Rabbi’s voice in the Lords may prove critical.

On Monday evening, Tim Whewell examines the JFS case and its implications in a programme on BBC Radio 4. Jewish: Blood or Belief? will be transmitted at 8pm on October 26.

The president of the Israeli Supreme Court, Judge Dorit Beinisch, attended the opening of the UK Supreme Court.