[1][3] Between 1905 and 1913 he contributed as an editor to the "Deutsche Angestellte Zeitung" ("German Clerical Workers' Newspaper") and he was also active as an author and producer of publications for the health insurance organisation.
[3] The position meant that he was able to exercise a powerful influence over the development and expansion of Germany's health insurance system, and he also became increasingly influential as a social policy strategist within the SPD, of which he had been an active member since 1903.
Although Communist activists were at the top of the government hit list, others with a record of activism in the SPD and the union movement also attracted the attention of the authorities.
In June 1935 he was again taken into "investigative custody", identified as the leader of a resistance group in Berlin comprising members of illegal organisations: Social Democrats and Trades Unionists.
[1] A few years later the assassination plot against Hitler failed in its primary objective but succeeded in making the government acutely nervous.
They dusted down a pre-prepared plan and on the night of 22/23 August 1944 mass arrests took place across Germany in an exercise identified as "Aktion Gitter".
What the people arrested had in common was that before 1933 they had been listed as active politically, usually as members of the Communist Party, the SPD or the trades union movement.
[1] The end of the war marked a return for Lehmann to mainstream politics in what was administered, between May 1945 and October 1949, as the Soviet occupation zone.
Then, through July 1945, he served as deputy chief of the Social Security Establishment for Greater Berlin,[1] a position from which he moved on to create the National Administration for Labour and Welfare Affairs ("Zentralverwaltung für Arbeit und Sozialfürsorge") in the zone relaunched, in October 1949, as the Soviet sponsored German Democratic Republic, retaining responsibility within that organisation as a vice-president of it till 1950.