Originally posted by CWyatt I don't think I agree, I don't see that photographing it is wrong if it can reasonably be seen from a public spot already.
It is, I believe, the matter of "expectation of privacy." Is your bedroom in the second story of your house and facing away from the street? If so, would you consider walking around in there naked? After all, you cannot reasonably see anyone outside so they shouldn't reasonably be able to see in.
But what if a neighbour climbs a tree in his back yard with his camera and manages to snap you through your window? Is that an invasion of privacy? I think it is. Granted if your bedroom fronts on to a busy street at ground level and you choose to leave the curtains open you may invite the intrusion. But where do you draw the line? What if you close the curtains but there is a small gap which a photographer manages to exploit?
I think the general idea is that "inside is private, outside is not." That makes it very easy to judge all of the above situations, even if sometimes it errs on the side of caution. Better that than the other way around. If you want to take a photo of someone inside you have to be inside with them. Then they have the trespass laws to defend their honour.
In fact, photographing someone on private property IS arguably a form of trespass.