Property, Contract, and Verification: The Numerus Clausus Problem and the Divisibility of Rights.

The law of every jurisdiction defines a set of well-recognized forms that property rights can take and restricts the creation of property rights that deviate from those forms. We argue that these restrictions serve not to standardize rights as others have argued but rather to aid verification of the ownership of rights offered for conveyance. We explore the feasible verification rules for property rights and illustrate the relationship between those rules and the structure of rights they support in the principal fields of property, including use rights to real and personal property, security interests, legal entities, and intellectual property. We offer a simple calculus for assessing the efficiency of alternative property rights regimes. We define clearly the difference between property rights and contract rights, clarify the connection between property rights and property rules, and illuminate the limits on specific performance as a contract remedy. Copyright 2002 by the University of Chicago.