Published: Lerner, Josh. "150 Years Of Patent Protection," American Economic Review, 2002, v92(2,May), 221-225.
The paper seeks to understand the impact of the patent system on innovation by examining shifts in the strength of patent protection across sixty countries and a 150-year period. An examination of 177 policy changes reveals that strengthening patent protection appears to have few positive effects on patent applications by entities in the country undertaking the policy change, whether filings in Great Britain or the nation making the policy change are considered. Cross-sectional analyses suggest that the impact of patent protection-enhancing shifts were greater in nations with weaker initial protection and greater economic development, consistent with economic theory. I address concerns about the endogeneity of these changes by employing an instrumental variable approach.