Patent Pools and Product Development: Perfect Complements Revisited∗

The conventional wisdom is that the formation of patent pools is welfare enhancing when patents are complementary, since the pool avoids a double-marginalization problem associated with independent licensing. The focus of this paper is on (downstream) product development and commercialization on the basis of perfectly complementary patents. We consider development technologies that entail spillovers between rivals, and assume that final demand products are imperfect substitutes. If pool formation either increases spillovers in development or decreases the degree of product differentiation, patent pools can actually adversely affect overall welfare by reducing incentives towards product development and product market competition—even with perfectly complementary patents. This significantly modifies and possibly even negates the conventional wisdom for many settings. The paper provides insights into why patent pools are uncommon in science-based industries such as biotech, despite there being strong policy advocacy for them.