You go to a peaceful protest. An agent records you or pulls fixed camera surveillance. Now you are a "person of interest". We already know law enforcement is

You go to a peaceful protest. An agent records you or pulls fixed camera surveillance. Now you are a "person of interest". We already know law enforcement is recording these events. But wait, you might not even have attended the event. You might have been walking to your job, your home, going shopping, meeting a friend. Tant pis pour toi... Perhaps my comment sounds over the top. But when the TSA (or, the real three letter acronyms behind it) can't even effectively maintain its no-fly list, particularly with respect to ruling out and removing false positives, or even having a policy and public interface for addressing this... Well, for one, my confidence is not particularly inspired.