 Further, if legitimate entitlement is sensitive to background changes, it is possible that the ongoing effect of an illegitimate acquisition and, more generally, of unjust violations of rights of others can become legitimate when circumstances change. Waldron’s primary example of supersession concerns “distributive considerations”. Waldron says that any plausible theory of property must be “circumstantially sensitive” and therefore must allow for the “possibility” of supersession (Waldron 1992b: 25; Waldron 2004a: 67–71). He gives an example in which the violation by one group of the legitimate rights of another group to a given waterhole is superseded by ecological catastrophe such that the interlopers acquire a right to share what they had wrongly begun to use. In these circumstances, 