Suppose you take a photo of your excavation, which happens to be within a modern town, and some bystanders end up in the photo. Later you want to publish the photo in a publication of the Society for American Archaeology (SAA). Guess what? They won't let you, unless you get a signed release form from every potentially identifiable person on the image. Well, since you took the photo several years ago, you won't be able to find those people, so you can't use the photo. Even if everyone in it is an adult, behaving legally in a public setting.
Why the regressive policy by the SAA? Because perhaps someone might sue the SAA over such a photo. Not that this has ever happened, and the chances of it happening are infinitesimally small. And irrespective of whether scholarship and knowledge will be advanced by your photo.
The current issue of The SAA Archaeological Record (March 2012) discusses this issue. John C. Whittaker wrote the SAA, complaining about the policy. He is clearly outraged, and I think I share his feelings. The SAA Board of Directors reconsidered the (long-standing) policy, and decided not to make any changes. Whittaker's letter is published, as is a reply from SAA President, Fred Limp.
To me, this is just another case of the SAA putting its own financial interests above the concerns of science and scholarship, in a situation where the potential gains (to knowledge) would seem to heavily outweigh the chances of financial harm.
Maybe I'm just cranky because I am not at the SAA meetings, going on right now. Nahhhhhh. I am getting a bunch of writing done on my sabbatical, and attending the SAA would not help on this score.