Reference? The ones I have been aware of have been very narrow, and there have been many public cases of the opposite (such as the recent Max Mosley case in the UK).

Generally the law seems to take a line similar to that of Wikipedia - that "public interest" means "general welfare". Note that this does not mean you can't publish details about the sex lives of celebrities, but you can't use public interest as a defense if you have participated in a crime to do so.