Look up supererogation, sunshine. Between that and Aquinas' "lex injusta non est lex" and "virtutem obligandi non habet", there is no end of room to distinguish between moral and legal obligations.

Whether or not I had lent you any money makes no difference to the illegality of my appropriation of found money that belongs to you, pursuant to the law of trover. In this scenario it would help me to think of myself as one of many possible creditors that that have a legitimate claim to your money. Hence the institution of bankruptcy courts that mediate our recovery in an orderly lawful fashion. The fact that my right to your repayment nowise translates to my entitlement to a full compensation, implies a conceptual incongruity between moral rights and legal remedies.

Terry, although I believe that there are duties in the state of nature, the scope of correlative natural rights is nowhere near as extensive as that of the privileges and immunities available in human relations under a social contract. For example, it makes sense to speak of fundamental natural rights to life, liberty, and the pursuit of happiness, but the right to a speedy trial by jury makes sense only in the social context that sustains the relevant peer-to-peer relationships and judicial institutions. Even in a setting of this sort, it is well established and clearly understood at common law, that necessity abrogates due process in the case of self-defense against aggression that the victim did not bring about through recklessness or negligence. Incidentally, Kant endorses an unqualified right of self-defense (ius inculpatae tutelae) that applies in domestic and foreign relations in equal measure, to the point of approving of warfare against a menacing increase in another state’s power, e.g. by its acquisition of territory, q.v. Die Metaphysik der Sitten 235 and 346.

Thanks for reading. See the ongoing collection here: http://larvatus.livejournal.com/tag/p210. Email me at zeleny@post.harvard.edu to receive periodic updates.

Rights are relational properties that only make sense within a society, as your Hohfeldian approach implies. Thus contractarian constructivism yields a predicate for self-defense, that aggression against oneself that the victim did not bring about through recklessness or negligence, temporarily reverts the parties to the confrontation to the state of nature. Your puzzles then resolve as a matter of determining the scope of bringing about.