" JCs" weren't held in secrecy in the nation of Israel:
Gates were PUBLIC venues:
The WTS even makes the connection to the gates and JCs
*** km 9/77 p. 6 par. 38 New Arrangements for Congregation Organization *** A judicial committee need not be limited to three members. The Scriptures do not give any specific number of older men who handled cases of wrongdoing in the early Christian congregation. Older men who served in the community during Israel’s history may have heard cases according to their availability at the city gate. For example, Boaz selected ten of the older men of the city to hear the matter he had to present. (Ruth 4:1, 2) However, everyone in the community was under the Law covenant arrangement then, and this added to the number for whom the older men were responsible. Within each congregation today, the number would not be that great in most cases, so three would usually be sufficient to have on a judicial committee. Where the gravity of what is involved warrants having four or even five experienced men to serve, this may be arranged.
*** it-2 p. 234 Legal Case ***
A person with a civil matter or a complainant in a criminal matter would bring his case to the judges. The other party would be called, witnesses were gathered together, and the hearing was conducted usually in a public place, most often at the city gates. (De 21:19; Ru 4:1) The judges would question the litigants and examine the evidence and testimony.
*** it-1 p. 893 Gate, Gateway ***
Gates were the centers of public assembly and public life. Broad places, such as the public square before the Water Gate in Jerusalem, were usually provided near the gates. (Ne 8:1) The gates were the city’s news centers not only because of the arrival of travelers and merchants but also because nearly all the workmen, especially those working in the fields, went in and out of the gate every day. So the gate was the place for meeting others. (Ru 4:1; 2Sa 15:2) The markets were located there, some of the gates of Jerusalem being named evidently for the commodities sold there (for example, the Fish Gate).—Ne 3:3.
At the city gates the older men of the city sat in judgment. (De 16:18; 21:18-20; 22:15; 25:7) Even kings at times held audiences or sat in judgment there. (2Sa 19:8; 1Ki 22:10; Jer 38:7) Because the judges, the prominent men of the city, the merchants, the businessmen, and a goodly number of people were usually at the gate, prophets often went there to make proclamations. Their messages delivered there would spread much faster. (1Ki 22:10; Jer 17:19) Other important announcements and official proclamations were also made there. (2Ch 32:6-8) It was in the public square before the Water Gate that Ezra read the Law. (Ne 8:1-3) Wisdom is pictured as crying out at the entrances of the gates for all in the city to become aware of its counsel. (Pr 1:20, 21; 8:1-3) Inasmuch as the gate was a news center, the good or bad works of the city’s inhabitants would become known there.—Pr 31:31.
*** it-1 p. 518 Court, Judicial ***
At the gate it was easy to acquire witnesses to a civil matter, such as property sales, and so forth, as most persons would go in and out of the gate during the day. Also, the publicity that would be afforded any trial at the gate would tend to influence the judges toward care and justice in the trial proceedings and in their decisions. Evidently there was a place provided near the gate where the judges could comfortably preside. (Job 29:7) Samuel traveled in a circuit of Bethel, Gilgal, and Mizpah and “judged Israel at all these places,” as well as at Ramah, where his house was located.—1Sa 7:16, 17.
(Deuteronomy 16:18) 18 “You should set judges and officers for yourself inside all your gates that Jehovah your God is giving you by your tribes, and they must judge the people with righteous judgment.
(Deuteronomy 22:15) 15 the father of the girl and her mother must also take and bring forth the evidence of the girl’s virginity to the older men of the city at the gate of it;
(Deuteronomy 21:18-21) 18 “In case a man happens to have a son who is stubborn and rebellious, he not listening to the voice of his father or the voice of his mother, and they have corrected him but he will not listen to them, 19 his father and his mother must also take hold of him and bring him out to the older men of his city and to the gate of his place, 20 and they must say to the older men of his city, ‘This son of ours is stubborn and rebellious; he is not listening to our voice, being a glutton and a drunkard.’ 21 Then all the men of his city must pelt him with stones, and he must die. So you must clear away what is bad from your midst, and all Israel will hear and indeed become afraid.