| Abstract: |
How does the publication of patents affect innovation? We answer this question
by exploiting a large-scale natural experiment—the passage of the American
Inventor's Protection Act of 1999 (AIPA)—that accelerated the public
disclosure of most U.S. patents by two years. We obtain causal estimates by
comparing U.S. patents subject to the law change with “twin” European patents
which were not. After AIPA's enactment, U.S. patents receive more and faster
follow-on citations, indicating an increase in technology diffusion.
Technological overlap increases between distant but related patents and
decreases between highly similar patents, and patent applications are less
likely to be abandoned post-AIPA, suggesting a reduction in duplicative R&D.
Firms exposed to one standard deviation longer patent grant delays increased
their R&D investment by 4% after AIPA. These findings are consistent with our
theoretical framework in which AIPA provisions news shocks about related
technologies to follow-on inventors and thus alters their innovation decisions. |