Dumpster diving is a great way to get free food and to shock people into awareness of waste, but I see a lot more to it. It is true that the activity is mildly illegal, because it is often seen as a form of trespassing or even stealing (which is ridiculous to me, but that's beside the point). People shouldn't be fooled; even though it is rare to be arrested or prosecuted for bin raiding, there is a risk of that (and the risk that goes with the stigma associated with such activities). And because of the risk, people who dumpster dive should believe that it's worth getting in trouble for. I think that's where the principles of Freeganism come in.
I personally see dumpster diving as a form of civil disobedience. I am violating the petty laws that protect trash (which is a representation of a wasteful society) in order to make a statement about the system that creates trash. Another part of freeganism is finding ways to reduce my own participation in that system. Dumpster diving provides a strategy for stepping out of consumer habits.
This topic came to my mind because of a recent police encounter. At our last dumpster ride event, we were confronted by the same officers who stopped us on our May dumpster ride (check the link for a recounting of that incident). During the first stop on our October ride, we where cornered by the police while we were behind the fence and in the dumpsters. We were caught red handed, trespassing! I have a problem with the way that authority holds the words of the law above the ideas that motivate people to break or keep the laws. The cops were also verbally abusive with us, assuming that we were less than them, merely because we were "breaking a law". How can they expect us to cooperate and keep our cool when they approach us with guns and sharpened words?
Even when stopped by authorities, it is rare to be prosecuted for such a "crime" as dumpster diving. We have not been contacted since the incident.