Just read an interesting article about photographer's rights.
http://www.krages.com/ThePhotographersRight.pdfLaws will vary from
country to country, but this is good stuff for the fearless photographer to know.
Here in Canada the cops have become quite sensitive to being photographed after ago a Polish immigrant was Tasered to death. Shortly thereafter I recall another incident where they seized a camera during mishap with an aggressive homeless person. So, it's good to know what rights you do have.
Thomas Hawk on his website writes " Know your rights. Nowhere are rights more misunderstood than with photographers today. Can you take photos of strangers on the street? Yes. Can you take photos of buildings from the street even after security guards tell you not to? Yes. Can you shoot into an open door from the street into a bar? Yes. Know your rights and stick up for them. This not only helps you but it helps other photographers."
I'd be a little nervous about snapping up shots of strangers (hotties at a nice beach for example) but on the other hand, there's good potential to come away with some really great pictures...
