The Iraq/Wife-beating Analogy

With regard to [the] wife-beating analogy, it's funny because I've also thought this in the same terms, though I would frame it differently as I think it can be broken down into much simpler issues:

If someone is beating their wife, should the already-established community norms for dealing with this sort of thing--i.e., calling the police--be used; or should the most heavily-armed neighbor (who coincidentally believes he has the best ideas about how to run a household) independently decide to take the law into his own hands and "liberate" the woman from her husband by force because, in his opinion, the police aren't effective?

After all, who is going to say the neighborhood isn't better off without the wife-beater?