 Of course, it may be impossible or severely difficult for A to duly compensate B for inflicting treatment T—as when T consists in killing B. Moreover, if it is impossible or severely difficult for A to duly compensate B for a given boundary crossing, A must not cross that boundary without B’s consent. The conjunction of the liability rule claim and the impossibility or difficulty of due compensation yields (the equivalent of) a property rule claim for B against A’s imposing T on B. The further conditions that render due compensation impossible or difficult boost what would otherwise merely be a liability rule claim against being subject to T into (the equivalent of) a property rule claim against being subject to T. As we see in the next section, Nozick thinks that such boosting conditions are pervasive. So, one of the things that Nozick is suggesting in his intricate chapter 4 is that, even the separateness of persons in itself only underwrites claims protected by liability rules, those claims need to be treated as though they are protected by property rules whenever due compensation for infringing upon them would be impossible or not feasible.