Baruch Litvin was an Orthodox Jewish layman of Mount Clemens, Michigan, remembered for the "Mount Clemens mechitzah case." In 1955 his synagogue, Congregation Beth Tefilas Moses, voted to introduce mixed seating. After the congregation refused to bring the matter to a beis din, Litvin went to the civil courts. The case lasted several years and reached the Michigan Supreme Court, which ruled in his favor in 1959, holding that a congregation defined as Orthodox could not introduce mixed seating. The case drew national attention and was an important factor in establishing the mechitzah as a defining mark of Orthodox synagogues in America.
Litvin gathered the rabbinic responsa and statements he had collected into the book The Sanctity of the Synagogue (1959). He later compiled the scholars' replies to Prime Minister David Ben-Gurion's inquiry "Who is a Jew?", published in English as Jewish Identity. In 1964 Yeshiva University honored him for his service to Torah Judaism and the American Jewish community.
The mechitzah campaign. The Rebbe strongly encouraged Litvin's efforts for a proper mechitzah, urging steadfastness in upholding Torah standards in communal life (IK 4476, 4575). He compared the great energy hidden in a tiny atom to the powerful potential within every Jew (IK 4575). On how to present the case in court, the Rebbe advised relying on a unified position of rabbinic authorities (IK 5521). After the ruling, he wrote that unwavering commitment to authentic Torah values brings true victory (IK 6890).
Jewish identity. Later letters connect with Litvin's work on the "Who is a Jew?" question: the Rebbe linked it to Parshas Yisro and the giving of the Torah, stressing the unity of the Jewish people (IK 8330).
Tanya, outreach and personal growth. Earlier letters show the Rebbe guiding Litvin personally: how to study Tanya, which is accessible to all and endlessly deep (IK 475); the hidden strengths in every Jew, as with the hidden tzaddikim (IK 486); the value of every effort in outreach (IK 643); and the need not to neglect one's own growth while helping others (IK 669). When Litvin was troubled by the state of Yiddishkeit in America, the Rebbe urged him to focus on strengthening it rather than on others' shortcomings (IK 8136).
Sources: Encyclopaedia Judaica ("Meḥiẓah"); My Jewish Learning; the Detroit Jewish News archives (1957, 1959, 1964); and the Rebbe's letters cited above.