David Farbstein was born in an Orthodox environment in Warsaw and studied law in Germany and Switzerland after his rabbinical training in Eastern Europe. After his naturalization in 1897, he settled as a lawyer in Zurich and simultaneously joined the Israelite Cultus Community and the Social Democratic Party. From 1896 to 1908, he was married to the physician and active social democrat Betty Ostersetzer. As a politician, he participated in the Social Democratic Party's struggle for the improvement of workers' living conditions. As a lawyer, he conducted many political trials and so-called women's trials. From 1922 to 1938, he raised the voice of progress as a national councilor and jurist in the assessment of crimes and offenders. Due to his religious ties, which were not self-evident for a social democrat, he insisted on a sharp separation between religious commandments and legal penalties, as well as the abolition of the death penalty. In Jewish organizations, the Swiss Israelite Community Federation, and the Israelite Cultus Community, he was an early advocate for equality both internally and externally, for the concerns of Orthodoxy, Eastern Jews, and Zionists, as well as against anti-Semitism. With his outspoken public reactions to anti-Semitism, he shocked Jewish tacticians and remained for a long time the spokesperson for a small minority that was disliked by many Jewish notables. The work of David Farbstein exemplifies the conflict situations of the first half of the 20th century within the Swiss Jewish and social democratic context. This work is made comprehensible through numerous articles by Farbstein from the social democratic and Jewish press, as well as many mostly unpublished sources, particularly from the archives of the Swiss Israelite Community Federation, the Israelite Cultus Community, and the Central Zionist Archives in Jerusalem.