Mishpatim, Shemos 23:3. The Majority Rules, but not always.

The possuk here says אחרי רבים להטות, which teaches that the opinion of the majority is to be followed. There is an interesting set of shittos about the extent of this halacha. See Minchas Usher here.

A. What if the mi’ut is smarter than the rov?
Obviously, the difficulty in assessing relative chochmo, and the multiplicity of types of chochmo, make this difficult to apply with any confidence in the real world, but here are the shittos.

1. Hagohos Ashri Avodoh Zoroh 1:3 holds that chochmoh never outweighs the supremecy of the rov.
2. The Ramban Sanhedrin 32a holds that in a Beis Din, Rov supercedes chochmoh, but in a non-beis din context, you can do whatever you want. In other words, Rov is no longer determinative, but neither is the mi’ut chachomim determinative.
3. The chinuch in 78 says that Rov is only dispositive against a mi’ut chochom in Sanhedrin, but not in any smaller Beis Din.
4. Rav Hai Gaon brought in the Ramban is unclear. He might hold that you always go after chochmoh, even in Sanhedrin Hagodol.

B. What about community matters?

1. Some hold that all community matters can be decided by a simple majority, which is binding on the minority. Rosh Tshuvos Klal 6 Simon 5, Tshovus Rashbo 1:781, and Yam Shel Shlomo Chulin 1:end of 51.
2. The Mordechai in BK 179 and BB 480 holds that majority cannot obligate the minority to do anything ever, but he brings that the Ram holds that the selectmen, the Tuvei Ho’ir, have the ability to bind their communities even to the extent of hefker, while the Rashbo limits that power to gedolei hador mamosh.
3. The Maharshdam in AC 37 and CM 421 says that community matters are decided by the chachemi ho’ir, and community money matters by its money men, the rich and influential, (who are assumed to be the most responsible and sophisticated when it comes to such things).
4. See beginning of four perek of Maseches Megilla. The Gemora distinguishes between the limited powers of the Tovei Ho'ir acting alone and the broader powers of the Tovei Ho'ir acting pursuant to a referendum.