Patenting inventions or inventing patents? Continuation practice at the USPTO

Continuations allow inventors to add new claims to old patents, leading to concerns about unintended infringement and holdup. We study how continuations are used in standard essential patent (SEP) prosecution. Difference in differences estimates suggest that continuation filings increase by 80%–121% after a standard is published. This effect is larger for applicants with licensing-based business models and for patent examiners with a higher allowance rate. Claim language is more similar for SEPs filed after standard publication, and late-filing is positively correlated with litigation. These findings suggest widespread use of continuations to draft patents that are infringed by already-published standards.