When do the USPTO examiners cite as the EPO examiners? An analysis of examination spillovers through rejection citations at the international family-to-family level

This paper empirically examines coincidences between “rejection citations” (i.e., those cited as grounds for rejections) added by the United States Patent and Trademark Office (USPTO) and “X/Y patent citations,” which are also added as grounds for rejections at the European Patent Office (EPO) within the same patent family, based on more than forty thousand families of triadic application sample. We consider the release timing of European search reports and the timing of rejection actions by the USPTO for the same family of patent applications. We find that the frequency of rejection (X/Y-equivalent) citation coincidences between the USPTO and the EPO according to family-to-family citation criteria increases after the release of search reports by the EPO. It suggests that the US examiners capture spillovers of search efforts from the EPO, namely, the USPTO examiners rely on prior art information collected and disclosed by the EPO. The results also reveal that International Search Reports (ISRs) prepared for Patent Corporation Treaty (PCT) applications, as well as applicant-submitted citations, play important roles for the convergence of rejection citations between the two patent offices. We furthermore find that the US examiners are less likely to add the same patent citations as the EPO examiners when rejections are persistently repeated at the USPTO. The methodology in this paper introduces the novel use of patent examiner citations to compare examiners’ citing behavior across jurisdictions.