Mishnah and Talmud
Despite the name, the classical semikhah did not actually require a literal laying on of hands; the operative part of the ceremony consisted of a court of three, at least one of whom himself had semikhah, conferring the authority on the recipient. Both the givers and the recipient had to be in the Land of Israel, but they did not have to be in the same place. In the Mishnaic era it became the law that only someone who had semikhah could give religious and legal decisions.
The title ribbi (or "rabbi") was reserved for those with semikhah. The sages of the Babylonian Jewish community had a similar religious education, but without the semikhah ceremony they were called rav. The Talmud also relates that one can obtain the title of Rabbi by those to whom he teaches or counsels.
After the failed revolution by Bar Kokhba in 132–135 CE, the Romans put down the revolt, and the emperor Hadrian tried to put a permanent end to the Sanhedrin, the supreme legislative and religious body of the Jewish people. According to the Talmud, Hadrian decreed that anyone who gave or accepted semikhah would be killed, any city in which the ceremony took place would be razed, and all crops within a mile of the ceremony's site would be destroyed. The line of succession was saved by Rabbi Yehuda ben Bava's martyrdom: he took no other rabbis with him, and five students of the recently martyred Rabbi Akiva, to a mountain pass far from any settlement or farm, and this one Rabbi ordained all five students. These new Rabbis were: Rabbi Meir, Rabbi Shimon, Rabbi Yehudah (ben Ila’i), Rabbi Yosi and Rabbi Elazar ben Shamua – an entire generation of Torah leadership. When the Romans attacked them, Rabbi Yehuda blocked the pass with his body allowing the others to escape and became one of Judaism's ten Rabbinic Martyrs himself by being speared 300 times. Hence, semikhah is also granted from one Rabbi to a new Rabbi, without the need of two witnesses, and the above five Rabbis carried on this tradition. The footnote gives a page of Talmud in Aramaic. See Sanhedrin 14a.
The exact date that the original semikhah succession ended is not certain. Many medieval authorities believed that this occurred during the reign of Hillel II, around the year 360 CE. However, Theodosius I forbade the Sanhedrin to assemble and declared ordination illegal. (Roman law prescribed capital punishment for any Rabbi who received ordination and complete destruction of the town where the ordination occurred). It seems to have continued until at least 425, when Theodosius II executed Gamaliel VI and suppressed the Patriarchate and Sanhedrin.
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