Law and order will be the first casualty when the shit hits the fan. Recent historical examples the world over, including New Orleans, Haiti, and Chile show that without policing, looting will become an immediate danger.
The following Guide to Looting When the SHTF by Thomas Northrop of No Bullshit Survival shows that survival and preparedness planning does not include just storing food, supplies, guns, and medicine, or creating tactical defense plans for your home and property. There will be organized gangs, whose sole method of acquiring necessities will be through looting. A friend recently mentioned that when discussing possible collapse scenarios at the water cooler, one of his office coworkers suggested that he would simply take what he needs from other people if it came down to it. Thus the looter mentality is not as isolated as we may think. In all likelihood, this person has already considered what he would do, how he would do it, and how far he was willing to go.
This is a reality, so understanding and accepting it as such is important now – so that you are fully prepared to deal with it if ever confronted by such a situation.