DM News, February 10, 2003 issue has an article "Privacy in Public Gets Much More Complicated" about whether we can expect any privacy when we are out in the world. Here's a useful quote:
"Surveillance might even be actionable under present law. When General Motors investigated Ralph Nader in the 1960s, Nader sued for invasion of privacy. The courts in New York upheld Nader's lawsuit because the surveillance was intrusive conduct designed to elicit information not available through 'normal inquiry or observation.'"
In Clearwater I was sometimes followed daily by PIs. I have lots of license plate numbers and a log of all this, plus videotape. When I moved back to Arizona I was followed here as well, and I have photos and plate numbers again. Gee, maybe I should take a certain cult to court? Or if it happens to you, you may have recourse.