His father was originally from Pressburg and had immigrated to Palestine in 1869, while his mother was a native of Jerusalem, with roots in the city dating to the late 18th century.

[1] But when the Aguda began to lean towards a modus vivendi with the Zionist leaders, Blau claimed that the Aguda had sold out to the Zionist movement and in 1937 a vote took place within the Edah HaChareidis in which the Neturei Karta party won by a landslide, with Agudah having to set up their own court, but later Rabbi Blau broke away from the Edah HaChareidis for various controversies which he claimed proved they were going in the direction of Agudah, and founded Neturei Karta with Rabbi Aharon Katzenellenboigen, and Rabbi Yaakov Meir Shechter.

[3] Blau was the secretary of an organization called Ramasayim Tsofim, which sought to build a Haredi agricultural settlement on the road to the grave of the Biblical prophet Samuel.

Prior to the Six-Day War, Blau even went so far as to propose moving to Jordanian controlled East Jerusalem to avoid the secular temptations of modern Israel.

[5] He was imprisoned many times for demonstrating against public violations of Shabbat, the conscription of religious women, the opening of a mixed-gender swimming pool, and other government policies.

[10] The match was opposed by Blau's two adult sons[2] and by the rabbinical court of the Edah HaChareidis, so the couple had to move to Bnei Brak,[11] but a year later they returned to Mea Shearim.