An excerpt from Rabbi Kaplan's Handbook of Jewish Thought.
The Sanhedrin was the supreme council of Israel. As long as it stood, it was the supreme court and legislative body in all matters of Torah law. As such, the Sanhedrin was entrusted with keeping and interpreting the Oral Torah.
It is a positive commandment to set up courts to interpret and decide questions of Torah law. It is thus written, "You shall appoint judges and officers in all your gates, which God is giving you" (Deut. 16:18).
The commandment includes the communal responsibility to appoint a duly ordained Sanhedrin. This precedes the establishment of other courts.
The Sanhedrin consisted of 71 judges. God thus commanded Moses, "Gather to Me 70 men of the elders of Israel... and bring them to the Tent of Meeting, so that they should stand there with you" (Numbers 11:16). This was the first Sanhedrin. Counting Moses himself, it consisted of 71 members.
Since the membership of the Sanhedrin is fixed by the Torah, its number cannot be changed.
Nevertheless, it was permitted to allow outside sages to enter into the deliberations of the Sanhedrin without voting privileges. Cases are therefore sometimes found in which a greater number participate in a decision.
The Sanhedrin could not render judgment unless its entire membership was present. If a member was absent, however, a temporary substitute could be appointed.
The leading sage of the Sanhedrin was appointed as its head, taking the place of Moses in the first Sanhedrin. His official title was "Head of the Sitting" (Rosh HaYeshiva). Later, however, he was referred to as the "President" (Nasi).
Any judgment issued by the Sanhedrin in the absence of the Nasi was invalid.
The Sanhedrin would sit in a semicircle, so all its members could see each other.
The second-ranking sage of the Sanhedrin was appointed as assistant to the Nasi. He was known as the "Master of the Court" (Av Beit Din). Both he and the Nasi were voting members of the Sanhedrin.
The Sanhedrin would sit in a semicircle, so that all its members would be able to see each other. They would also have an equal view of all witnesses testifying.
Out of respect for the Nasi, the Av Beit Din would sit at the extreme right. He would be followed by the Nasi, and then by the rest of the Sanhedrin in order of their capability.
Qualifications for Membership
Every member of the Sanhedrin had to be distinguished in Torah knowledge, wisdom, humility, fear of God, indifference to monetary gain, love of truth, love of fellow man, and good reputation. It is thus written, "You shall provide out of all the people, able men, who fear God, men of truth, disdaining unjust gain, and place them over [the people]" (Exodus 18:21). It is likewise written, "Take from each of your tribes, wise men, with understanding and full of knowledge, and I will make them your leaders" (Deut. 1:13).
Judges had to have knowledge of science and mathematics to adapt Torah law to all possible situations.
Since the Sanhedrin had to be competent to render judgment in all cases that came before it, all its members had to be expert in all areas of the Torah. They also had to have enough knowledge of science and mathematics to be able to adapt Torah law to all possible problems.
Members of the Sanhedrin likewise had to have knowledge of other religions, as well as the teachings of idolatry and the occult arts, so as to be able to render judgment in cases involving these matters. For this reason, even studies which were normally discouraged or forbidden, were permitted to members of the Sanhedrin when these studies were required for judgment.
The Sanhedrin was required to hear all testimony directly, and not through an interpreter. It is therefore preferable that its members be familiar with all the languages spoken by Jews around the world.
When a foreign language is used in testimony, the Sanhedrin must have at least two members who speak that language to examine the witnesses. There must also be a third member who understands the language. These three members then constitute a minor court (beit din) of three, who can report the testimony to the entire body. Once testimony has been accepted by a minor court, it is no longer considered second-hand testimony.
In order that the Sanhedrin command the utmost respect, its members must be of good appearance, and free of bodily defect. Therefore, a person who is blind, even in one eye, cannot be a member of the Sanhedrin.
Age and Lineage
Similarly, the members of the Sanhedrin must command respect as mature individuals. Therefore, it is preferable that each member be at least 40 years old, unless he is incomparable in wisdom and universally respected. Similarly, it is preferable that the head of the Sanhedrin be at least 50 years old. Under no condition should a person under 18 be appointed to the Sanhedrin.
A person who is very old may not sit on the Sanhedrin, since he is apt to be too severe. The same is true of a man who is sterile, or even childless. A Sanhedrin containing any such member is not validly constituted. Therefore, if a member becomes very old or sexually maimed, he must be replaced.
It is preferable that the members of the Sanhedrin be chosen from people of unbroken descent, as in the case of all positions of authority. It is required, however, that all members of the Sanhedrin be of Jewish parentage...
Every member of the Sanhedrin must be of unblemished family, as was the first Sanhedrin under Moses. Therefore a bastard (mamzer, i.e., the son of an adulterous or incestuous union) is ineligible for membership and renders a Sanhedrin invalid…
It is preferable that the Sanhedrin contain Kohen-priests and Levites as members. It is thus written, "You shall come to the Kohen-priest and Levites, and to the judge who shall be in those days" (Deut. 17:9). Nonetheless, a Sanhedrin is valid even without Kohen-priests and Levites.
Every member of the Sanhedrin must be ordained, following a tradition from Moses. It is thus written, "Moses did as God commanded him. He took Joshua... and laid his hands on him, commanding him, as God spoke through Moses" (Numbers 27:22-23). Moses also laid his hands on the other elders, ordaining them as members of the Sanhedrin. These, in turn, ordained others, generation after generation, in an unbroken line of ordination from Moses.
Although Moses ordained the first Sanhedrin with the actual laying of hands, this was a special case, and was only done that one time. All subsequent ordinations were performed orally, granting the subject the title of "Rabbi" and declaring that he is "ordained with the right to judge cases involving fines."
Ordination must be conferred by a court of three, containing at least one ordained member. It can be done either in person, or by messenger or letter. A single court can ordain many individuals at once.
Therefore, as long as a single ordained person is alive, the tradition of ordination can remain unbroken. The ordained person can form a court with two unordained men, and ordain as many others as needed. The unordained members of the court, however, could then never be ordained themselves, since that would give them an interest in the case.
Some authorities maintain that ordination must be performed by day. In this respect, it is no different than any other judgment.
Ordination can only be conferred in the Land of Israel. The entire area included in the First Commonwealth is valid for such ordination. Both the ordaining court and the persons being ordained must be within its borders. If a Sanhedrin was ordained in the Holy Land, however, it can then function in other lands as well.
It is forbidden to appoint judge who does not have the necessary qualifications.
To qualify for ordination, a man must have all the qualifications necessary for membership in the Sanhedrin. However, if he later becomes disqualified from membership in the Sanhedrin because of age or physical disability, his ordination is still valid.
To qualify for ordination, one must be expert in all areas of Torah law. However, now that the Oral Torah has been committed to writing, it is sufficient that one be familiar enough with all the written authorities to render judgment in all cases.
The greatest Torah scholars of each generation are automatically qualified for ordination. It is thus written, "You shall go to the... judge who shall be in those days" (Deut. 17:9). This indicates that each generation has its own standard.
It is forbidden to appoint a man to the Sanhedrin or any other court if he does not have the necessary qualifications, even if he has other good qualities. To do so is to violate the commandment, "You shall not respect persons in judgment" (Deut. 1:17).
On the Temple Mount
The Sanhedrin originally convened in the Temple area, in the Chamber of Cut Stones (Lishkat HaGazit). This was a chamber built into the north wall of the Temple, half inside the sanctuary and half outside, with doors providing access both to the Temple and to the outside.
The place where the Sanhedrin convened was actually outside the sanctuary area. The Sanhedrin would sit while in judgment, and it is forbidden to sit within the sanctuary area. On the other hand, part of this chamber had to be inside the sanctuary area, since the Sanhedrin judged many things involving priests and the Temple service, and this had to be done within the Temple grounds. Moreover, questions would often arise during the divine service, when it is forbidden for a Kohen-priest to leave the sanctuary area. There was also a requirement that there be direct access from the Great Altar (mizbeach) to the Sanhedrin.
It was only in this chamber that the Sanhedrin could perform all its functions, including the trial of capital offenses.
However, in the year 3788 (28 CE), when the Sanhedrin relinquished its power to try capital offenses, it moved to another room on the Temple Mount, and then into the city itself. When Jerusalem was destroyed in 3828 (68 CE), the Sanhedrin moved to Yavneh. During the ensuing century, the location of the Sanhedrin alternated between Yavneh and Usha. From there it moved consecutively to Shafar'am, Beth She'arim, Sephoris, and Tiberias. It remained functioning in Tiberias until shortly before the completion of the Talmud.
During the persecutions of Constantinius (4097-4121; 337-361 CE), the Sanhedrin had to go into hiding, and it was eventually disbanded. There is a tradition that it will be in Tiberias that the Sanhedrin will be restored.
The traditional ordination (semicha) was thus abolished in the year 4118 (358 CE). The Sanhedrin and other duly constituted courts cannot be established until this ordination is reinstituted.
Jewish Courts Today
What is called "ordination" today is not true ordination, but rather, a certification that the individual is expert in certain areas of Torah law. Moreover, it implies that he has the permission of his teachers to render public decisions; without such permission it is forbidden.
Such ordination, however, in no way implies competence to serve on the Sanhedrin.
Therefore, no rabbinical court today can judge cases on its own authority. The only authority that such courts have is as agents of the earlier ordained courts. In this capacity, they can only judge commonly occurring cases involving actual loss on the part of the litigants. However, infrequently occurring cases, and those involving punitive damages or fines, require duly ordained judges, and therefore cannot be judged in contemporary rabbinical courts.
Some say that like all other positions of authority, ordination can be established by common consent as well as by unbroken tradition. However, only those living in the Land of Israel are counted with regard to matters dealing with authority. Therefore, ordination can be reestablished by the consent of the religious leaders in the Holy Land, even if they represent a minority of world Jewry.
Therefore, if all the religious leaders and authorities living in the Land of Israel were to agree to ordain a suitable individual, he would be considered duly ordained. He would then have the authority to set up a court and ordain others. Thus, the Sanhedrin and other courts could be restored.
The Messiah can only be recognized by a duly ordained Sanhedrin.
It is foretold that the restoration of the Sanhedrin will precede the coming of the Messiah. God thus told His prophet, "I will restore your judges as at first, and your counsellors as in the beginning; afterward you will be called the city of righteousness, the faithful city. Zion shall be redeemed with justice, and those who return to her, with righteousness" (Isaiah 1:26-27). This restoration, however, can only take place in such a time as willed by God.
The Messiah will be a king of Israel, and as such, he can only be recognized by a duly ordained Sanhedrin.
There is a tradition that the Sanhedrin will be restored after a partial ingathering of the Jewish exile, before Jerusalem is rebuilt and restored. There is also a tradition that Elijah will present himself before a duly ordained Sanhedrin when he announces the coming of the Messiah. Like all events in the Messianic drama, the restoration of the Sanhedrin can only occur at the time decreed by God.
An excerpt from Rabbi Kaplan's Handbook of Jewish Thought.