The Beth Din of the priests or Court of the Priests ("house of judgement of the priests" Hebrew: ) was the court of Jewish law, composed of twenty-three senior priests that would oversee the day-to-day operation of the Temple in Jerusalem, including the sacrifices and offerings, the verification of Aaronic lineage, and the safeguarding of the vessels used in the Temple. The term Beth Din shel kohanim is mentioned by name only twice in Tannaitic and once in Amoraic literature, and has caused confusion regarding its meaning.
The Beth din of the priests functioned on behalf and support of the Sanhedrin (Hebrew: ), and performed its duties in the eleven Ammoth located between the western wall of the Holy of Holies structure and the western wall of the azarah (temple courtyard). This area was also known in Hebrew as achurei Beth HaKaporeth ("behind the Holy of Holies").
Generally, the authority of the original Beth din shel Kohanim superseded that of the Sanhedrin in areas of interest relating to the Temple and to those related to the priesthood.
Some scholars are of the opinion that the 23 member body of the Beth din shel Kohanim also served in the Sanhedrin as a third of the 71 members serving therein.
The first recording of creation of the Beth din shel Kohanim is traditionally ascribed by Sifri to the verse:
Therefore thou and thy sons with thee shall keep your priest's office for every thing of the altar, and within the vail; and ye shall serve: I have given your priest's office unto you as a service of gift: and the stranger that cometh nigh shall be put to death.-- Numbers 18:7, KJV
Though the Beth din of the priests is not explicitly mentioned in this verse, nor elsewhere in the Hebrew Bible.
"It is all one whether a woman is the widow of an Israelite or the widow of a priest, her Ketubah is one mina. The court of the Priests14 used to levy 400 zuz15 [as Ketubah] for a virgin, and the Sages did not reprove them" The Mishnah translated Herbert Danby, 1933 Page 245
Midrashic and Talmudic sources record that in both the first and Second Temples the Beth din shel Kohanim served their duties of temple operation and oversight of the priesthood.
The investigating properties of the Beth din shel Kohanim is described by scholars as being in addition, and secondary, to the investigating of Kohanic lineage performed by the Sanhedrin.
Similarly, it is presumed that the Sanhedrin would perform a one-time investigation elevating the investigated Kohen from "status quo" status to kohen meyuchas status ("Kohen-lineage verified by Beth-din") whereas the Beth din shel Kohanim would continuously monitor the status of duty-active Kohanim in terms of their keeping to the numerous Torah and Rabbinic law that accompanies the duties and privileges of priesthood.
The status of priests as teachers of the Law is portrayed in multiple instances in the Hebrew Bible. Generally, the Law endows the priests with authority to instruct proper Mitzvah performance of commandments as written in the Law and explained by the Sanhedrin elders. Torah verses generally describe the instruction of the priest as both final-word and reliable (Deuteronomy 21:5), with the absence of a Kohen with Torah instructive abilities described as a national misfortune (2 Chronicles 15:3).
Torah commentators discount the notion that the Kohen is qualified to instruct by right of his Kohanic lineage alone. But state that is both his Kohanic lineage along with thorough knowledge of Torah law that qualifies the Kohen for Torah instruction
Based on rabbinic literature, the Beth din shel Kohanim consisted solely of Kohanim of verified patrilineal descent ("Kohanim meyuchashim") from Ahron HaKohen, as opposed to the Sanhedrin which was composed of members of all twelve tribes of Israel.
Mishna text confirms that the Beth din shel Kohanim was authorized to levy the death penalty ("dinei nefashot"). Rabbeinu Chananel was of the opinion that the Beth din shel Kohanim also oversaw the appointing and rotation of the 24 priestly divisions. Similarly, the Beth din ran the daily temple operations and possibly controlled the initiation ceremonies of inaugurating new vessels ("Kli sharet") to be used in the temple.
Another item of interest to the Beth din shel Kohanim is quoted in tractate Ketuboth, where the Beth din would ascertain that the ketubah of a Bat-Kohen bride would list a base rate of four hundred zuz (as opposed the common two hundred zuz) (Mishnah Ketuboth 1:5 and 10:2).
Mishnaic sources imply that the Beth din shel Kohanim played an active role in designating the monthly Rosh Chodesh holiday. As per the mishna in tractate Rosh HaShanah quoting an instance where
Tuvia the physician .. saw the new (moon).. and his son and his freed servant, and the Kohanim admitted (the testimony) of him and his son and disqualified his servant. And when they came before the beth din (hagadol) they admitted him and his servant and disqualified his son(s testimony)-- Rosh HaShana 1:7
Rabbi Menachem Schneerson, in his Igrot Kodesh work explains the involvement of the Beth din shel Kohanim as the primary initiating body of the Rosh Chodesh festival due to the unique Korban that is to be brought due to the Rosh Chodesh holiday -over which the Beth din shel Kohanim would preside.
Apparently, the Beth din shel Kohanim played an active role in the Yom Kippur temple service; which included the appointing of a Kohen to escort the scapegoat sacrifice to the desert. Mishnah commentators point out that it is also likely that the Beth din shel Kohanim was dutifully meticulous that the Kohen Gadol would carry out his duties as required.