As a photographer in the USA I’ve had more than one instance of people trying to bully me because I had a pro level camera. The worst offenders have been security guards.
If you’ve ever been in the situation you know what I mean, and if not you should be prepared. You get treated like your a criminal, they threaten to take away your gear etc.
Of course of you are standing on private property you can be asked to leave and are required to do so, but DID YOU KNOW that in most cases even a police officer can’t take away your camera without a court order? After some hassles I decided to look into it some years back, and there’s even a book called The Legal Handbook for Photographers that I picked up. It goes in depth into these issues, but if you just want the basics heres some places to start.
Photojojo just wrote a great article outlining photographer rights so check it out here. Most of the info info came from a lawyer named Bert Krages who wrote the afore mentioned book. He also has a PDF called The Photographers Right that outlines the basic rights. I suggest you downland that and keep in in your bag should you ever have a confrontation.