In 1920, he returned to the Indies and took up a civil servant (ambtenaar) post in the Department of Justice.[1][9] In May 1927 he was elected to the Volksraad for the Indo Europeesch Verbond.[1][10] He continued to hold the post through the 1930s and until the Japanese invasion in 1942.[11]
He resigned from the Indo Europeesch Verbond in 1947, citing irreconcilable differences between his views and those of the current leadership of the party.[12]
During the Dutch–Indonesian Round Table Conference in 1949 he was one of the leaders of a faction representing Dutch and Indo people in the talks.[2] His faction, which was by far the largest, was also led by J. H. Schijfsma and J. Verboom and represented the right-wing Grooter Nederland Actie (Greater Netherlands Action), New Guinea settlement organizations, and the organization of former prisoners of war (NIBEG).[2][13] (Of the other two smaller Indo factions at the talks, one represented the Eurasian League, and the other was a tiny faction representing the pro-Indonesian Indo Nationale Partij.[2]) Blaauw and his faction felt they were ignored during the talks, and so they refused to attend the final meeting out of protest.[2]
After Indonesia achieved its independence from the Netherlands, he resigned from the civil service and traveled to Europe in December 1949.[14][15] There he continued to advocate for Indos and Dutch people living in Indonesia, working a leader of an organization called the Vereniging van Indische Nederlanders (Association of Indies Dutch).[16][17] He was also active in organizations working to ensure continued Dutch control over Netherlands New Guinea.[18] Around 1960 he was active in another organization, NASSI (Nationale Actie Steunt Spijtoptanten Indonesië), which was chaired by William Lemaire, a fellow Indo lawyer who had been a Catholic National Party member of parliament in the Netherlands and had since become a professor at Leiden University.[19][20] The purpose of that organization was to support Dutch and Indo people still living in Indonesia, and to expedite their relocation to the Netherlands if necessary.
^Van der Veur, Paul W. (1971). The Eurasians of Indonesia: A Political-historical Bibliography. Ithaca, NY: Modern Indonesia Project, Cornell University. p. 92. ISBN9780835761086.