Nor had I ever hear of Germany ordering a person with German citizenship out of Germany never being allow to return.
That's what is and has been done with several Germans, who had dual nationalities (here: Turkish and German), but only since some years, when the relevant law was changed.
Actually, the situation in the 1970's/1980's/early 1990's was different.
I wondered how this happened with Lauck ... and I really was kind of wrong.
He easily could have got a German passport. But obviously, he didn't ask for.
Because the administration knew about this (in the earlier trials, he was referred to as "Deutsch-Amerikaner", German-American
), he was expelled. Afterwards, this (and the trial) have been the legal estoppal for applying for a passport.