So an institution was established just to adjudicate differences of opinion among sages so as to determine the ultimate Halacha, and it was termed the Sanhedrin.
The Torah spoke of its prototype at a certain point, when Moses was apparently overburdened by the number of goodly souls who “stood around him from morning till evening” (Exodus 18: 13) in order “to seek G-d’s will” (Ibid. 15) and to have him “inform them of G-d’s decrees and laws” (Ibid. 16). Yitro, his father-in-law, suggested that Moses would soon grow too weary to carry out so taunting a task day after day, and so he should set up a judicial system to represent him for the people. He advised Moses to “provide out of all the people able men who fear G-d, who are men of truth and who hate greed” and to set them up as leaders and judges (Ibid. 21-22).
G-d later confirmed that when He commanded Moses to in fact “assemble … seventy men of the elders of Israel” (Numbers 11:16) to serve as its Supreme Court, its main legislative body in all Torah laws, its arbiter of all things touching upon the Oral Torah — its Sanhedrin. In Ramchal’s words, the esteemed members of the Sanhedrin were entrusted to “safeguard the mitzvot of the Torah, so that G-d’s word would be obeyed” by the entire Jewish Nation.
Along such lines, they (and their successors) enacted both civic and ceremonial rules that came to be known as the Rabbinic Laws, which were intended to ensure the sanctity and observance of G-d’s Torah. And whenever a controversy arose among its members as to the final Halacha, the matter would be put to a vote, and the majority ruling would be enacted.
Astoundingly enough, the Sanhedrin even had the power to “set aside one of the Torah’s mitzvot when the purpose (in doing that) was to safeguard the Torah itself”, Ramchal points out. And so, for example, they disallowed us to blow on the Shofar on a Rosh Hashanah that fell out on a Shabbat, so as to ensure the sanctity of the Shabbat (see Rosh Hashanah 29a and Sukkot 42a).
When the Sanhedrin was disbanded (425 C.E.), its authority was passed on to the sages of each generation, down to our own. That is based on the idea that G-d gave each qualified Torah scholar the right (and responsibility) to decide questions of Halacha following the prescribed methodology.
And so there followed a long line of eminent rabbis who decided the actual Halacha for their own and subsequent generations from the time of the Talmud (until 499 C.E.) and through the eras of the Savoraim (until 589), the Gaonim (until 1038), the Rishonim which lasted unti l the death of Rabbi Yoseph Caro who authored the pre-eminent Code of Jewish Law known as the Shulchan Aruch (1574), which was followed by the era of the Acharonim which is still in place at the present time.
And all that has served to inform us of what G-d requires of us at any one time so that we might draw close to Him, which is the point of it all.
Rabbi Yaakov Feldman has translated and commented upon “The Gates of Repentance”, “The Path of the Just”, and “The Duties of the Heart” (Jason Aronson Publishers). His works are available in bookstores and in various locations on the Web.