Kiddush HaChodesh: Judicial vs. Sovereign Function of Beis Din

This shiur explores a fundamental chakira in the nature of Kiddush HaChodesh: whether it requires the Sanhedrin functioning in its judicial capacity or in its sovereign capacity as representative of Umas Yisrael. The Gemara (גמרא) in Rosh Hashanah 25b discusses a case where witnesses were interrogated and the Beis Din did not have time to declare "mekudash" before nightfall—the month becomes me'uber. The Gemara asks why the Mishna needs two cases (when the Beis Din saw the new moon themselves vs. when witnesses came), and answers that one might have thought that chakiras eidim is like techilas hadin, and therefore "mekudash mekudash" could be said at night as gmar din. The Gemara rejects this because "ki chok l'Yisrael hu mishpat l'Elokei Yaakov"—even the sovereign function of declaring mekudash mekudash is subject to the gezeiras hakasuv of mishpat and must be done by day. The Rambam (רמב"ם) in Sefer HaMitzvos (mitzvah (מצוה) 153) states that Kiddush HaChodesh requires Beis Din HaGadol. The Ramban (רמב"ן) asks four fundamental questions on this ruling: (1) The Rambam himself writes that until Bayis Sheni they were mekadesh al pi re'iyah, implying Beis Din HaGadol existed, yet the Gemara in Sanhedrin says Beis Din could not judge dinei nefashos forty years before the Churban because they left lishkas hagazis—meaning there was no functional Beis Din HaGadol. (2) The Torah (תורה) should have said "lecha" (to you, Moshe) rather than "lachem" (to you, plural) if Moshe alone suffices as keNeged shivim v'echad. (3) The Rambam says if chas v'shalom there were no Beis Din and no semuchim in Eretz Yisrael, we couldn't be mekadesh—but this tragedy already happened. (4) The Gemara says three mumin are good for Iber HaShanah, not necessarily the full Sanhedrin of seventy-one.