Time in Purgatory: Determinants of the Grant Lag for U.S. Patent Applications

The impacts of two recent changes in US patent policy depend on the length of time it takes for an invention to go through the examination process. Concerns over the distributional effects of these changes were expressed during policy debates. We use data on U.S. patent applications and grants to determine the factors influencing the length of the patent examination process. We augment this analysis with interviews of patent examiners, leading to a better understanding of the examination process. Our analysis finds that differences across technology are most important. Inventor characteristics have statistically significant effects, but the magnitudes are small.