A great Hayek quote from Law, Legislation, and Liberty:
The understanding that “good fences make good neighbours”, that is, that men can use their own knowledge in the pursuit of their own ends without colliding with each other only if clear boundaries can be drawn between their respective domains of free action, is the basis on which all known civilisation has grown. Property, in the wide sense in which it is used to include not only material things, but (as John Locke defined it) the “life, liberty and estates” of every individual, is the only solution men have yet discovered to the problem of reconciling individual freedom with the absence of conflict. Law, liberty, and property are an inseparable trinity. There can be no law in the sense of universal rules of conduct which does not determine boundaries of the domains of freedom by laying down rules that enable each to ascertain where he is free to act. (Hayek 1973, 1:107)
Property rights are essential to a free society. But “property rights” without clear boundaries aren’t property rights at all, they’re an affront to the rule of law.