Separate seating for men and women during davening is an ancient practice whose origins hark back to the procedure followed in the Beis ha-Mikdash. During the Festival of Succos, when joyous throngs filled the Beis ha-Mikdash to witness the festivities of Simchas Beis ha-Shoeivah, it was not possible to keep the women totally separate from the men. The rabbis were concerned lest the unavoidable mingling of men and women lead to kalus rosh (excessive frivolity) and thereby mar the sanctity of the holy service. To prevent this from happening, a balcony was erected upon which the women could stand totally apart from the men but still witness the festivities. The Talmud attests that the need for this balcony was considered to be so pressing that its construction was approved even though it is basically forbidden to expand or modify the original structure of the Beis ha-Mikdash. 
Following the example set by our Sages in the Beis ha-Mikdash, shuls the world over were built with separate sections for men and women. Some shuls had a raised women’s gallery like the balcony in the Beis ha-Mikdash, while others had men’s and women’s sections on the same floor but with a thick wall between the two. This concept of mechitzah (separation) was so taken for granted, so undisputed, that it was not even mentioned in the Shulchan Aruch as a requirement for a Beis ha-Knesses.
With the advent of the haskalah (Jewish Enlightenment) in Western Europe just over 200 years ago, and its wholesale attack on religious observance (including Shabbos, kashrus, milah, etc.), mechitzos in shuls were also compromised or done away with over the vigorous protest of Rabbonim who decried this desecration and forbade davening in any place of worship that lowered or removed the traditional mechitzah.
With the immigration of Jews to the United States in the late 1800’s, these transplanted modern ‘temples” continued their practice of mixed pews and/or halachically unacceptable mechitzos. In the free and easy atmosphere of America, even the more traditional synagogues began to question the necessity of a mechitzah. And so, eventually, the following questions—unthinkable a century earlier—were posed to the venerable poskim in the U.S.: Is a mechitzah halachically required? How high does a mechitzah have to be?
Reason for the balcony in the Beis ha-Mikdash In order to answer these questions correctly, we must first examine what purpose the balcony in the Beis ha-Mikdash served. We explained earlier that a balcony was constructed to prevent kalus rosh, excessive frivolity. The Talmud does not, however, elaborate on how, exactly, the balcony prevented kalus rosh. There are two possible ways to understand this:
The two views of the poskim
There are two schools of thought among contemporary authorities as to the practical halachah. Many poskim hold that the purpose of the mechitzah is to block the men’s view of the women. Accordingly:
As stated previously, a mechitzah was a universal, standard feature of every Jewish place of worship. The women’s section, whether in the balcony or at the back or side of the shul, was totally separated from the men’s. Such a separation was fundamental to shul architecture, as basic as positioning the amud at the front of the shul and a bimah in the middle. It was and still is part of the standard model for a Jewish place of worship.
Rav M. Feinstein, however, after establishing that the requirement for separating men and women during prayer services is a Biblical obligation, holds that the essential halachah follows the second approach that we mentioned earlier. Although he agrees that it is commendable and praiseworthy to maintain the age-old traditional mechitzah, he nevertheless rules that the widespread practice of many shuls to lower the mechitzah somewhat is permitted according to the basic halachah. As long as the mechitzah is high enough to effectively block out any communication or interaction between the men’s and women’s sections, it is a halachically valid mechitzah. Accordingly:
1. Succah 51a. The Biblical source for the separation of men and women, says the Talmud, is found in the verse in Zecharyah in which the prophet foretells the eulogy of Mashiach ben Yosef, where men and women will be seated separately. If separate seating is required even at so solemn an affair as a eulogy, how much more so must separate seating be required on a joyous occasion!
2. Tzitz Eliezer 7:8.
3. Led by Rav Shelomo Ganzfried, author of Kitzur Shulchan Aruch, and Maharam Ash, disciple of Chasam Sofer, and countersigned by the Divrei Chayim. The proclamation is published in Lev ha-Ivri. See also Maharam Shick, O.C. 77 and Zichron Yehudah 1:62 who also voiced strong objections to any tampering with the traditional mechitzah.
4. Rambam (commentary to the Mishnah Succah 5:2)
5. Tosfos Yom Tov (commentary to the Mishnah Succah 5:2).
6. Rambam Hilchos Lulav 8:14.
7. Piskei Rid Succah 51; Meiri Midos 2:5; Korban Eidah (Yerushalmi Succah 5:2) as explained in Divrei Yoel 1:10.
8. Rambam, Hilchos Lulav 8:12 and Hilchos Beis ha-Bechirah 5:9; Meiri Succah 51a; Tiferes Yisrael Succah 5:6; Aruch ha-Shulchan ha-Asid 11.
9. Maharam Shick 77; Rav E. M. Bloch (Taharas Yom Tov, vol. 6); Divrei Yoel, O.C. 10; Shevet ha-Levi 1:29.
10. Igros Moshe, O.C. 1:39 and in various other responsa; Seridei Eish 2:14. See also ruling of Rav Y. E. Henkin (quoted in Teshuvos Bnei Banim, pg. 12).
11. Shabbos 92a.
12. Igros Moshe, O.C. 4:31.
13. Igros Moshe, O.C. 3:23; 3:24; 4:30; 4:31.
14. Igros Moshe,O.C. 1:42.
15. Igros Moshe, O.C. 1:43; 3:23.
16. Igros Moshe, O.C. 4:29.
17. Igros Moshe, O.C. 4:32.
18. Igros Moshe, O.C. 3:23; 3:24; 4:31.
Weekly-Halacha, Text Copyright © 2011 by Rabbi Neustadt, Dr. Jeffrey Gross and Torah.org.
Rabbi Neustadt is the Yoshev Rosh of the Vaad Harabbonim of Detroit and the Av Beis Din of the Beis Din Tzedek of Detroit. He could be reached at [email protected]