"Public Photography Laws - Photographing Police and Public Places"

 Glenn Reynolds in Popular Mechanics discusses an issue this blog has touched on in the past -

Legally, it's pretty much always okay to take photos in a public place as long as you're not physically interfering with traffic or police operations. As Bert Krages, an attorney who specializes in photography-related legal problems and wrote Legal Handbook for Photographers, says, 'The general rule is that if something is in a public place, you're entitled to photograph it.' What's more, though national-security laws are often invoked when quashing photographers, Krages explains that 'the Patriot Act does not restrict photography; neither does the Homeland Security Act.' But this doesn't stop people from interfering with photographers, even in settings that don't seem much like national-security zones.

Tennessee law student Morgan Manning has compiled a list of incidents in which individuals were wrongly stopped. Cases like that of Seattle photographer Bogdan Mohora, who was arrested for taking pictures of police arresting a man and had his camera confiscated. Or NASA employee Walter Miller, who was stopped for photographing an art exhibit near the Indianapolis City-County Building and told that "homeland security" forbade photos of the facility. More recently, a CBS news crew was turned back from shooting the oil-fouled gulf coastline by two U.S. Coast Guard officers who said they were enforcing "BP's rules."

Unfortunately, Manning notes, although such hassling is generally illegal, it's hard for the average citizen to get redress in court...

If it's an issue that interests you, I've got a link to Carlos Miller's Photography is Not a Crime blog in the sidebar to your right. And if you have a professional interest in the subject, whether as a photographer or as counsel, look at the Legal Handbook for Photographers at the link in the quote from the article.