Sanhedrin 2A

מתני׳ דיני ממונות ⁠– בשלשה, גזילות וחבלות ⁠– בשלשה, נזק וחצי נזק, תשלומי כפל ותשלומי ארבעה וחמשה ⁠– בשלשה.

Mishnah: Cases concerning monetary law are adjudicated by 3 judges. Cases concerning robbery and personal injury are adjudicated by 3 judges. Cases concerning damage that one is responsible for because he or his property caused the damage are adjudicated by 3 judges as well. Likewise, cases concerning payment for half the damage, which is paid in the event that an ox whose owner has not been warned that it gored more than two times gores another animal (see Exodus 21:35); cases concerning payment of double the principal by a thief who was caught stealing (see Exodus 22:3); and cases concerning payment of 4 or 5 times the principal by a thief who slaughtered or sold a stolen ox or a lamb (see Exodus 21:37) are all adjudicated by 3 judges.

האונס והמפתה והמוציא שם רע ⁠– בשלשה, דברי רבי מאיר.

Cases concerning one who rapes or one who seduces a virgin girl, and must therefore pay the girl’s father 50 silver shekels (see Deuteronomy 22:29, Exodus 22:15); and cases concerning a defamer who falsely asserts that his wife was not a virgin when she married him, and brings false witnesses who testify that she committed adultery while betrothed to him and who must therefore pay the girl’s father 100 silver shekels as well as receive lashes (see Deuteronomy 22:13–19): All of these are adjudicated by 3 judges; this is the statement of R' Meir.

וחכמים אומרים: מוציא שם רע ⁠– בעשרים ושלשה, מפני שיש בו דיני נפשות.

And the Rabbis say: Cases concerning a defamer are adjudicated by a court of 23 judges, which is the type of court authorized to judge cases of capital law, because this case includes the possibility of becoming a case of capital law. The husband brings witnesses that his wife committed adultery. If she is found guilty, she is liable to receive the death penalty. This punishment applies to the witnesses if they are exposed as conspiring witnesses.