The 56-year-old chief inspector's rape and assault of his girlfriend were domestic matters, and had no direct influence on his service, judges at the Bavarian administrative court ruled, the Süddeutsche newspaper reported on Thursday.
The man could not be stripped of his civil servant status, nor sacked, because when convicted of the rape and two assault charges, he was given less than a year's suspended sentence for those crimes.
In this case the judge said it played in the man's favour that he had admitted what he had done - and his victim had remained in the relationship after the attacks.
He was given a suspended prison sentence of 11 months and two weeks. Had the sentence been two weeks longer, he would have been sacked immediately the Süddeutsche said.
A representative of Munich's head of police told the administrative court deciding on the man's career, that there was "absolutely no trust" in the man among his colleagues, and that they would not want to have him handling cases.
It would be impossible to defend to the public any decision to keep him in office, he said.
The man raped his girlfriend in 2006 when they were on holiday together - supposedly because he wanted more sex than she did. And on two occasions over the following two years, he poured beer over her and punched her in the face - because she did not want to have sex with him.
Bavarian police must continue to have him on their books and in uniform, although he has been demoted two ranks, the paper said.