The questions before the judges in Courtroom No. 1 of Britain’s Supreme Court were as ancient and as complex as Judaism itself.

On the surface, the court was considering a straightforward challenge to the admissions policy of a Jewish high school in London. But the case, in which arguments concluded Oct. 30, has potential repercussions for thousands of other parochial schools across Britain. And in addressing issues at the heart of Jewish identity, it has exposed bitter divisions in Britain’s community of 300,000 or so Jews, pitting members of various Jewish denominations against one another…

By many standards, the JFS applicant, identified in court papers as “M,” is Jewish. But not in the eyes of the school, which defines Judaism under the Orthodox definition set out by Jonathan Sacks, chief rabbi of the United Hebrew Congregations of the Commonwealth. Because M’s mother converted in a progressive, not an Orthodox, synagogue, the school said, she was not a Jew — nor was her son. It turned down his application.

That would have been the end of it. But M’s family sued, saying that the school had discriminated against him. They lost, but the ruling was overturned by the Court of Appeal this summer.

In an explosive decision, the court concluded that basing school admissions on a classic test of Judaism — whether one’s mother is Jewish — was by definition discriminatory. Whether the rationale was “benign or malignant, theological or supremacist,” the court wrote, “makes it no less and no more unlawful.”

The case rested on whether the school’s test of Jewishness was based on religion, which would be legal, or on race or ethnicity, which would not. The court ruled that it was an ethnic test because it concerned the status of M’s mother rather than whether M considered himself Jewish and practiced Judaism.

“The requirement that if a pupil is to qualify for admission his mother must be Jewish, whether by descent or conversion, is a test of ethnicity which contravenes the Race Relations Act,” the court said. It added that while it was fair that Jewish schools should give preference to Jewish children, the admissions criteria must depend not on family ties, but “on faith, however defined.”

The same reasoning would apply to a Christian school that “refused to admit a child on the ground that, albeit practicing Christians, the child’s family were of Jewish origin,” the court said.

Even more to the root of the question is religions that consider their law superior to the law and legal system of the state. Unless you’re in a theocracy – when you can have bits of your body lopped off for offending some judge.