In 1922 to 1925 and from 1928 to 1931 he was a delegate in Saeima of the Republic of Latvia (Latvian Parliament),[5] where he worked together with the left-wing parties, and to protect the rights of minorities in general and Jews in particular.

[8] Lazerson was also active in the association of Hapoel Hatzair and Tzeirei Zion and was its deputy on the Zionist General Council.

[10] In March 1934, Lazerson visited Mandatory Palestine to attend a meeting of the Zionist General Council.

[11] Following the Latvian coup d'état of Ulmanis on May 15, 1934, Lazerson was banned as a leftist, at the same time as abolishing cultural autonomy for Jews.

[18] Later, he stayed in the US, worked in Justice Department, and then went on to serve as a professor of public international law at Columbia University.