Working Paper: CEPR ID: DP9468
Authors: Dietmar Harhoff; Georg von Graevenitz; Stefan Wagner
Abstract: Post-grant validity challenges at patent offices rely on the private initiative of third parties to correct mistakes made by patent offices. We hypothesize that incentives to bring post-grant validity challenges are reduced when many firms benefit from revocation of a patent and when firms are caught up in patent thickets. Using data on opposition against patents at the European Patent Office we show that opposition decreases in fields in which many others profit from patent revocations. Moreover, in fields with a large number of mutually blocking patents the incidence of opposition is sharply reduced, particularly among large firms and firms that are caught up directly in patent thickets. These findings indicate that post-grant patent review may not constitute an effective correction device for erroneous patent grants in technologies affected by either patent thickets or highly dispersed patent ownership
Keywords: Intellectual Property; Opposition; Patent Litigation; Patent Thickets; Patents and Postgrant Review
JEL Codes: L13; L20; O34
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| Concentration of patent holdings (L49) | Probability of opposition (D79) |
| Patent thicket density (O34) | Incidence of postgrant validity challenges (L49) |
| Patents granted to insiders (O36) | Likelihood of opposition (D79) |
| Density of patent thickets (O34) | Opposition likelihood (D79) |