Die Schweizermacher (1978)

This romantic drama follows two policemen whose job is to investigate the lives of foreigners who have applied for Swiss citizenship. Among the applicants they must screen are a French psychiatrist and his wife, and a ballet dancer. The married couple are quickly accepted, but the dancer's life offers some objections. However, since the younger policeman has fallen in love with her, there is a chance that she, too, will win Swiss citizenship.