I have argued before that police often behave as if they are legally dictator of their immediate area, and frequently assume they can issue orders, however asinine, to anyone in their visual range. Of course this is legally not true (though I suppose it is legally true if you take into account that courts and the minimal accountability processes that exist for cops never punish them for such behavior).
Here is a great example. The 2-minute TSA freeze drill, with the TSA yelling at people -- already through security -- within their visual range for moving. I think they are ripping off Heinlein - was this in Starship Troopers?