Abstract
This paper explores the interface between two important institutional pillars of market exchange – Intellectual Property (IP) law and Antitrust law – in light of a theory of property rights incompleteness. This theory interprets property as an incomplete bundle of both defined and undefined rights over actual and potential uses of given resources and defines externalities as joint claims over rival production uses of undefined entitlements, irrespective of whether the object of property rights has a tangible or intangible nature. The paper argues that traditional distinctions between physical property and IP based on attributes of tangibility, rivalry and excludability are misleading and bases on the substantial homogeneity of property rights and IPRs an argument supporting the complementarity between IP law and Antitrust law. Far from being an unjustified ex-post limitation to existing property rights, likely to undermine ex-ante incentives, Antitrust intervention represents one of the means by which incompletely specified property rights (both intellectual and tangible) might be redefined over time as externalities emerge.