After 9/11, the government began encouraging local police, private security and everyday Americans to report so-called "suspicious activity" that may indicate a security threat. More than 15,000 reports are already compiled in one database that can be searched nationwide by law enforcement authorities. Taking photos of landmarks, walking "nervously" and writing in a notebook are all activities that have led to people being stopped and questioned. Could you be next?
Directed and produced by Carrie Ching