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 between 1978 and 1996. Opposition can be considered an early form of patent validity challenge suit. In our sample, 8.6 percent of the patents are attacked in opposition proceedings. Using citation and patent family indicators we show that valuable patents are more likely to be attacked, and that opposition is particularly frequent in areas with strong cumulative patent numbers and with high technical or market uncertainty. We comment on the implications of these results for the design of the patent and litigation system. (100 words