Patent Claims and Patent Scope

Patent scope is one of the important aspects in the debates over “patent quality.” The purported decrease in patent quality over the past decade or two has supposedly led to granting patents of increased breadth (or “overly broad” patents), decreased clarity, and questionable validity. Such patents allegedly diminish the incentives for innovation due to increased licensing and litigation costs. However, these debates often occur without well-defined measurements of patent scope. This paper explores two very simple metrics for measuring patent scope based on claim language: independent claim length and independent claim count. We validate these measures by showing that they have explanatory power for several correlates of patent scope used in the literature: patent maintenance payments, forward citations, the breadth of patent classes, and novelty. Using these data, we provide the first large-scale analysis of patent scope changes during the examination process. Our results show that narrower claims at publication are associated with a higher probability of grant and a shorter examination process than broader claims. Further, we find that the examination process tends to narrow the scope of patent claims in terms of both claim length and claim count, and that the changes are more significant when the duration of examination is longer