Determinants of Opposition against EPO Patent Grants – The Case of Biotechnology and Pharmaceuticals

We analyze the determinants of opposition to biotechnology and pharmaceutical patents granted by the European Patent Office (EPO) between 1978 and 1996. Opposition at the EPO is the most important mechanism by which the validity of a European patent can be challenged. In our sample, 8.6% of the patents are attacked in opposition proceedings. We show empirically that the likelihood of opposition increases with patent value, and that opposition is particularly frequent in areas with strong patenting activity and with high technical or market uncertainty. We comment on the implications of these results for the design of the patent and litigation system