Long Live Patents: the Increasing Life Expectancy of Patent Applications and its Determinants

Relying on a comprehensive dataset including detailed information on all patent applications filed to the EPO from 1980 to 2000 and on the renewal of those of them that were granted, this paper presents the first survival time analysis of the determinants of patent length. The results are twofold: first, they clearly establish that the life expectancy of patent rights has significantly increased over the past decades despite a small decline in the average grant rate. Second, they show that some filing strategies very strongly influence the overall length of patents, possibly due to induced delays in the examination process. This suggests that such strategies may result in higher and longer lasting legal uncertainty on the markets, with unknown consequences on the dynamic efficiency of the patent system.