A dayan serves as a judge on a beth din, a rabbinical court applying Jewish law to matters including conversion to Judaism, the granting of a religious divorce, a get, disputes between Jewish businesses or individuals who choose to submit to rabbinical rather than civil arbitration, and questions of personal status such as confirming Jewish lineage; the qualification for serving as a dayan is considerably more demanding than for ordinary rabbinic ordination, requiring specialized training in the procedural and evidentiary law governing rabbinical courts beyond the general legal and textual mastery ordinary semicha certifies.
A beth din typically sits with three dayanim for most matters, a plurality required under Jewish law for a valid court, and its decisions, while not enforceable through state power in most countries, carry significant religious weight for observant Jews, particularly regarding personal status questions such as a valid religious divorce, without which a Jewish woman is considered unable to remarry within Jewish law regardless of any civil divorce already granted; the resulting cases in which a husband refuses to grant a get, leaving his wife an agunah, a chained woman unable to remarry religiously, have become a significant subject of communal and legal advocacy across the Jewish world.