Seth Godin:

If you see something, say something...Why would anyone hesitate to report (something dangerous)?  Because we've been taught to shut up and keep our heads down.  Because the authorities don't actually like gadflies or neighborhood-watch busybodies.  So they make it uncomfortable to speak up.  In many police departments, the first suspect in a dispute is the one who took the time to call it in.

Poke the Box, p.36-37