Property II
Privity of Estate
Privity of estate has two components—horizontal privity and vertical privity.
Both forms of privity are required to enforce the burden of a covenant against a successor to the covenantor, but neither is required to enforce the covenant to enforce the covenant against the original covenantor.
(Technically, privity of estate just means there is a mutual interest in land or a successive interest in land, regardless of whether it is horizontal or vertical, which Lucas likes.)