More arcane and inconsistent decisions from the movie censor, The British Board of Film Classification.
I can't see why it should give an 18 to The Baader-Meinhof Complex when it only rated The Dark Knight Batman film a 12A. Of the former it notes the strong language, nudity and "intense scenes" - an odd phrase. Baader-Meinhof is certainly an intense film in that it is a serious dramatisation of terrorist actions and motivations. It's a movie for a grown-up sensibility.
Dark Knight features highly stylised violence and many scenes of brutality, such as when Batman repeatedly beats the Joker during an interrogation or when the Joker appears to push down a man's face onto a sharp object. The BBFC makes a virtue of the "disguising" of these actions. That's not the word for it. There is no question about what we are seeing: if the speed with which the camera looks away is the major criterion, then someone needs their head examined. Violence here is a crucial feature of its commercial appeal: it's part of the genre.
Oliver Stone's W. has a mystifying 15 for its "strong reality footage" which "includes sight of some badly disfigured corpses, including children. Although the images are quite brief it was felt that they were too graphic and potentially upsetting to younger teens." But these teens probably see images of this sort on the evening news every week. The violence implied by these images is actual, not an exploitative element of a genre.
I can't help but wonder whether the BBFC takes too much account of the seriousness of a movie in relation to sex, violence and language. W. and Baader-Meinhof are serious in intention: both throw light on dysfunctional establishments and war. Batman is a fantasy, something that colours the BBFC's perception of the effect of its violence.
At some level the nitwits of the BBFC plainly factor in political intentions in their assessment of a movie, as if to say, "Oh, this is a serious film, that fact alone magnifies the effect of the sex/violence/cuntings." And let us not forget, Warner Bros and others lobbied the BBFC for the more lucrative 12A rating of The Dark Knight.