Are Patent Fees Effective at Weeding out Low-quality Patents?

The paper investigates whether patent fees are an effective mechanism to deter the filing of low-quality patent applications. The study analyzes the effect on patent quality of the Patent Law Amendment Act of 1982, which resulted in a substantial increase in patenting fees at the U.S. Patent and Trademark Office. Results from a series of difference-in-differences regressions suggest that the increase in fees led to a weeding out of low-quality patents. About 14 per cent of patents in the lowest quality decile were filtered out, and the effect was especially visible for companies with a large patent portfolio. The study has strong policy implications in the current context of concerns about declines in patent quality.