교섭단체
Bastian was, from 29 March 1983 until 18 February 1987, an elected member of the Greens in the German Federal Parliament. Between 10 February 1984 and 18 March 1986, he was an independent member of Parliament having separated from the Green's Parliamentary group several times over his opposition to the rotation principle for leadership then enforced in the Greens. He was then deselected by the Green Party.