In ancient times, the court system of Israel was dominated by two forms of large courts. The smaller courts, known as “small sanhedrins,” were composed of 23 sages each and were located throughout the land of Israel. The large court, composed of 71 of the greatest sages of Israel, known as the Great Sanhedrin, served as both a judicial court and a legislative body and sat in the semi-circular "Chamber of Hewn Stones" in the Holy Temple in Jerusalem.
As a legislative body, the Great Sanhedrin played a critical role in interpreting Jewish law. In fact, the Torah scholarship of the 71 sages was considered so great that the members of the Great Sanhedrin were empowered to enact new laws, if necessary.
The judicial system of ancient Israel revolved around the testimony of witnesses. In order to convict a person of theft or of a physical crime, a minimum of two witnesses was necessary. To disprove his accusers, the defendant could also bring witnesses.
In capital cases, the Sanhedrin appointed different judges to investigate the evidence of both sides and report their findings to the assemblage. One interesting provision of the Sanhedrin's procedures was that if a person in a capital case was convicted unanimously, the conviction was overturned and the person was acquitted on the grounds that the defense had not been properly and thoroughly presented, as evidenced by the unanimous guilty verdict.
After the destruction of the Temple in 70 C.E., the Great Sanhedrin reconvened in Yavneh and afterwards in various cities in the Galilee, before being disbanded in 425 C.E.