If you’re standing on public property, you can shoot anything the naked eye can see, explains Ken Kobre, professor of photojournalism at San Francisco State University and author of one of the seminal textbooks on the subject.
…But that apparently doesn’t stop security guards, cops, and others from intimidating and sometimes arresting those who try it.
Lawrence Lessig had a little bit to say about this in Free Culture, though his real point there was about copyright issues related to photography. Here, at the bottom of page 33, he makes the point that I’m getting at:
[E]arly in the history of photography, there was a series of judicial decisions that could well have changed the course of photography[...]. Courts were asked whether the photographer, amateur or professional, required permission before he could capture and print whatever image he wanted. Their answer was no.
Various forces have been chipping away at this basic presumption of freedom to photograph ever since, but Lessig rightly credits this early decision with creating the cover necessary for consumer photography to emerge and boom as it did.