Indeed, that's a very difficult line to draw. In the US we have the concept of a public figure, and I'll admit I have no idea how that's actually defined. That being said I've also wondered if it's too blunt a concept. Are public figures entitled to any privacy, and if so, where is that line? I see celebrities being hounded by paparazzi while trying to go about their daily lives, for example, and while I understand the principles behind why that's legal, I have to imagine it's a real drag.