Patent Pendency, Learning Effects, and Innovation Importance at the US Patent Office

We replicate and extend the results of Regibeau and Rockett (2010) on a new data set. We confirm that importance of a patent and the delay in approval at the patent office are negatively related. This relation survives even if we do not control for learning effects and so suggests that carefully defining the technology is sufficient to recover the negative relation. We use new measures to test for the existence of patent "thickets", thereby ruling out some strategic considerations in delay behaviour. It appears that delay is attributable to patent office, not filer, behaviour in our sample. A more careful analysis of the possible effect of examiner workload finds that larger workloads per examiner are associated with shorter approval time, lending credence to Lemley and Shapiro's concern that heavy workloads force examiners to devote too little time to each patent review.