European patent opposition outcomes in biotechnology

Oppositions to patent grants are a means to attack competitors and protect a firm's own patent portfolio. Extant literature has analyzed the determinants of oppositions, while the drivers of opposition outcomes are less known. We study 290 EPO biotech patent oppositions filed in 2012-2019. There are three possible outcomes of oppo-sition proceedings: patent revocation, patent amendment, and opposition rejection. We find that opponents who know the patent's technology are more likely to obtain a patent revocation, while opponents who compete in the product market with the patent owner are more likely to receive a rejection.