Bruce Schneier, who specializes in security issues, has an interesting article on photographers and security in his most recent newsletter. You should read the entire article but here’s a quote:
“Fear aside, there aren’t many legal restrictions on what you can photograph from a public place that’s already in public view. If you’re harassed, it’s almost certainly a law enforcement official, public or private, acting way beyond his authority. There’s nothing in any post-9/11 law that restricts your right to photograph.
This is worth fighting. Search “photographer rights” on Google and download one of the several wallet documents that can help you if you get harassed; I found one for the UK, US, and Australia. Don’t cede your right to photograph in public. Don’t propagate the terrorist photographer story. Remind them that prohibiting photography was something we used to ridicule about the USSR. Eventually sanity will be restored, but it may take a while. ”
Here’s a link to a summary article with more links.