Halakha is binding and authoritative

Halakha comes from a root meaning to walk, and the tradition counts 613 commandments in the Torah, of which a large number concern the Temple and are not currently practicable. Everything else is derived, and the machinery of derivation is what the tradition mostly consists of.

The Mishnah, compiled around 200, records rabbinic legal opinion in six orders covering agriculture, festivals, women and marriage, damages and civil law, holy things and purity. The Gemara, the record of subsequent debate in the academies of Babylonia and the land of Israel, was combined with it to form the two Talmuds, of which the Babylonian became authoritative. Talmudic argument is characteristically unresolved: it preserves minority opinions, records objections without always answering them, and reasons at length about cases that could not arise.

Because a body of argument is not a usable code, later authorities produced codes. Maimonides's Mishneh Torah in the twelfth century arranged the whole law topically and without citing sources, which was controversial precisely because it obscured the reasoning. Joseph Karo's Shulchan Aruch of 1565, with the glosses of Moses Isserles recording Ashkenazi practice where it differed from Karo's Sephardi rulings, became the standard reference and remains so.

Alongside the codes runs the literature of responsa, answers by individual authorities to specific questions put to them, which is where the law meets circumstances the codes did not anticipate: electricity on the Sabbath, autopsy, artificial insemination, the status of a soldier missing in action.

There is no central authority and no supreme court. A halakhic position acquires standing through the reputation of its author and its acceptance by communities, which makes Jewish law more like a common-law tradition of accumulated precedent than a legislated system.

What separates the modern movements is not whether halakha is valuable but whether it obligates.

Orthodoxy holds it binding in full and divinely grounded. Conservative Judaism holds it binding and revisable, and its Committee on Jewish Law and Standards has issued rulings permitting driving to synagogue on the Sabbath where distance would otherwise prevent attendance, ordaining women from 1985, and admitting openly gay candidates to ordination from 2006. Notably it sometimes issues more than one valid ruling on a question, which is itself a statement about how the system works. Reform treats ethical law as binding and ritual observance as a matter of informed choice.

The practical consequences are severe where personal status is concerned. Conversion, divorce and descent are governed by halakha, and Orthodox authorities do not accept non-Orthodox conversions or divorces, so a person may be considered Jewish by one movement and not another, with real effects on marriage and, in Israel, on law. Reform's recognition of patrilineal descent in 1983 sharpened this considerably, since the rabbinic rule reckons Jewish status through the mother.

Two comparisons illuminate what kind of thing halakha is. Islamic sharia is the closest analogue in any tradition: a comprehensive law derived from scripture and prophetic practice through jurisprudence, covering worship, diet, family and commerce, with schools of interpretation and no single authority in the Sunni case, and the parallel extends to the historical fact of Jewish and Muslim jurists working in the same intellectual world. Christianity, by contrast, decided very early, in the dispute recorded in Acts and in Paul's letters, that gentile believers were not bound by the Mosaic law, and Christian tradition therefore developed canon law as church regulation rather than as revealed legislation binding the whole of life.