He was a co-founder of the Liberal Democratic Party of Germany (LDPD) and the Free German Youth (FDJ) in Leipzig.

Under his leadership, the LDPD developed some small scale contacts with its West German counterparts, the Free Democrats (FDP).

[2] On 13 October 1989, Gerlach was the first important East German politician to publicly question the monopolistic role of the SED.

[1] A few days later, on 18 October, SED leader Erich Honecker was finally deposed by his own Politburo.

[1] He held this post until April 1990, when the State Council was abolished in a prelude to reunification with West Germany.

Gerlach was a signatory of the Berliner Alternatives Geschichtsforum,[3] which promoted more positive views on GDR history.

Critics of the former communist regime have described these publications co-authored by former GDR high functionaries (e.g. Gerlach, Gerald Götting, Hans Modrow etc.)