Sanhedrin Chapter 11, Mishnah 4 - The final Mishnah dealing with the rebellious elder (zaken mamre). Its subject: where the zaken mamre is judged and where he is executed. Let us recall the foundation of the law: a zaken mamre does not require a formal warning, but he does require a cautionary warning. Once it is explicitly heard that the High Court, the Sanhedrin, ruled in a certain way, and nevertheless he returned to his city and instructed others or acted himself contrary to the Sanhedrin's ruling - he is immediately liable to the death penalty, provided there are two witnesses that he did so.
The language of the Mishnah:
"Ein memisin oso lo b'veis din sheb'iro" - They do not put him to death in the court in his city. When the witnesses come and claim that this person acted in a way that makes him a zaken mamre, he is judged in a local court, a court of twenty-three in that city, since it is a capital case. However, if they convict him, they do not execute him there. This is the point of the Mishnah: they do not execute him in his city, but rather bring him up to Jerusalem.
"V'lo b'veis din sheb'Yavneh" - Nor in the court in Yavneh. Meaning, even if the Great Sanhedrin is sitting in a location other than Jerusalem, such as Yavneh, where it sat for a certain period after the Destruction - they do not perform executions from there at all. Everything must be done in Jerusalem, the place that God chose.
"Ela ma'alin oso l'veis din hagadol sheb'Yerushalayim" - Rather, they bring him up to the Great Court in Jerusalem. He must be brought to the Great Sanhedrin, to the High Court in Jerusalem.
"Umeshamrin oso ad haregel umemisin oso baregel" - And they guard him until the festival and put him to death on the festival. Even there, they do not put him to death immediately, as is done in other capital cases, but rather they guard him and wait until one of the three festivals - Pesach, Shavuos, or Sukkos - and then they execute him.
A technical note: when the Great Court is not sitting in the Chamber of Hewn Stone (Lishkas HaGazis) on the Temple Mount, right in the Temple complex, capital cases are not judged anywhere in the Land of Israel. The assumption in our Mishnah is, for example, that the case was judged while the Sanhedrin sat in Jerusalem, and afterward, it moved temporarily to Yavneh: executions are not carried out in Yavneh, and if the Sanhedrin returns to Jerusalem - they will be able to carry it out there.
The reasoning of Rabbi Akiva:
The reason is to generate publicity and make the matter known, as the verse states: "And all the people shall hear and fear, and do no more presumptuously," which is the opinion of Rabbi Akiva. Since the verse establishes that all the people must hear, fear, and not act presumptuously again, it must be carried out when everyone is gathered and present - when everyone goes up for the festival three times a year. Obviously, they do not execute him on Yom Tov itself, as that is forbidden, but rather on Chol HaMoed; and if it was on Shavuos, which has no Chol HaMoed, they execute him on the day after, since everyone is still present in Jerusalem on that day, and consequently they will know and hear about it.
The approach of Rabbi Yehuda:
Rabbi Yehuda disagrees and holds that they do not do so. According to him, the verse does not state that all the people must see him being executed, but only that they must hear about it - and why shouldn't they hear about it in their own places, after they have left Jerusalem? Conversely, there is another value at stake: we do not delay justice and we do not cause the condemned unnecessary suffering. By virtue of the mitzvah to "love your fellow as yourself," there is no reason to prolong his suffering and leave him waiting in prison until that terrible day arrives; if he is sentenced to die, he should be executed immediately.
Therefore, Rabbi Yehuda says: "Ein me'anin es dino shel zeh, ela memisin oso miyad" - They do not delay his judgment, but rather execute him immediately. They execute him in his place, like in any other capital case, without bringing him up to Jerusalem and without waiting for the festival. "V'chosvin v'sholchin shluchim b'chol ham'komos" - And they write and send messengers to all places. They send messengers throughout the Jewish world with a notice to be publicized in all communities: "Ish ploni ben ploni nischayev misah b'veis din" - So-and-so, son of so-and-so, was sentenced to death in court. The letter announces that so-and-so was executed by the court, and notes that this was done because he went against the Sanhedrin and issued a halachic ruling contrary to them under the status of a zaken mamre. The Mishnah does not explicitly detail this, but it is obviously the case. Thus, the approach of Rabbi Yehuda is that it is sufficient for everyone to hear about the matter, without being present at the time of the execution.
As for the halachah, and this is the opinion of the Rambam, the ruling follows Rabbi Akiva: they bring him up to Jerusalem, wait for the festival, and execute him on Chol HaMoed or on the day after Shavuos, so that everyone will know and be aware of the matter.
Four mitzvos that carry an obligation of publicity:
It is worth noting that there are four mitzvos in the Torah where an obligation of publicity is stated, so that "they will hear and fear":
A zaken mamre.
An ed zomem - which will be the subject of the next chapter and the next tractate.
A meisit - one who persuades people and brings them to idol worship.
A ben sorer u'moreh - if indeed such a thing ever occurred, his execution also requires publicizing.
In summary: In this Mishnah we learned that we do not execute the zaken mamre in the court in his city, nor even in the court in Yavneh. Rather, we bring him up to the Great Court in Jerusalem, keep him under guard until the festival, and execute him on the festival - according to the opinion of Rabbi Akiva, due to the verse, "And all the people shall hear and fear", and the halachah follows this opinion. Rabbi Yehudah disagrees due to the issue of delaying justice, and holds that we execute him immediately, and we write and send messengers to publicize the matter in all places. We also discussed the four mitzvos that require publicizing, all of which were also carried out in Jerusalem.