Eugene Volokh demonstrates that the positive rights/negative rights distinction can’t really do the work libertarians want it to do.
Eugene observes that private property always constitutes a restriction on negative liberty, because it consists of the right to exclude others from the use of that property. In particular, he points out that private property in land restricts the liberty that others would otherwise naturally enjoy to walk on that land.
But he goes on to describe that negative liberty claim as “morally untenable.” That’s the part I can’t fully follow. That I should be prevented by law from taking your personal property — e.g., apples from a tree you have planted and tended — makes good Lockean sense. You produce the apples; therefore they’re your apples.
But how does it come about, morally, that it’s your land? As Nozick points out in Anarchy, State, and Utopia Locke’s account of “mixing one’s labor with the soil” is more or less incoherent, and the Lockean condition of leaving “as much and as good land” unclaimed unravels backwards once there’s no unclaimed land left. (Whoever took the last bit of unclaimed land didn’t leave “as much, and as good” for the next claimant, so he can’t properly take it. But then whoever took the next-to-last bit didn’t leave “as much, and as good” either, and so backwards until the very first appropriation is shown to be unjust.)
From a practical point of view, private property in land has huge advantages. But since land (setting Holland aside for the moment) can’t be made but only appropriated by denying others the right to use it, I find it hard to understand how anyone could have a natural, rather than a prescriptive, right to landownership.