'Fuzzy' Software Patent Boundaries and High Claim Construction Reversal Rates

Bessen and Meurer (2008) theorize that a breakdown in notice of patent boundaries caused the patent litigation surge of the 1990s. They argue a prime source of this breakdown was the proliferation of software patents with particularly uncertain scope. In this paper I seek evidence that software patent scope is more uncertain by extending the empirical literature on claim construction reversal rates to determine whether the Federal Circuit has been more likely to find error in district court construction of software patents. Not only do I find that it has, since 2002 software patents account for forty percent of the difference between the Federal Circuit's high claim construction reversal rate and its lower average reversal rate on all other patent issues. These results are cause for optimism because, in general, the application of existing claim construction law has been more predictable than many have feared. However, that optimism does not extend to software claim construction, which remains highly unpredictable