, Volume 117, Issue 2, pp 825–843 | Cite as

The choice of examiner patent citations for refusals: evidence from the trilateral offices

  • Tetsuo WadaEmail author


Utilizing a novel methodology based on international family-to-family patent citation data, this paper directly compares X/Y patent citations (i.e., those cited as grounds for rejections, equivalent to “blocking patents” in the US) between major patent offices. Remarkable discrepancies between the offices were revealed, despite the common patentability criteria of novelty and inventive step to generate citations. This paper then introduces a simple cosine similarity measurement between a family of X/Y patent citations and all citations added globally to the same original application. How the discrepancies of X/Y patent citations at the European Patent Office (EPO) and the US Patent and Trademark Office (USPTO) relate to the characteristics of applications and longitudinal aspects of office actions were also examined. X/Y patent citations from both the EPO and USPTO commonly show that the range of patent application classes is positively correlated with divergent reasons for refusal, suggesting that costly examinations lead to diversified X/Y patent citations. One novel methodological feature of this paper is that examiner citations across jurisdictions are comparable if we employ family-to-family citations and common criteria for the X/Y citation category. Furthermore, unlike the normal citation-generating process where a citing document adds citations to prior art only once, this paper represents the first attempt to analyze a citation network with multiple citing opportunities from separate parties. We find that the variance of citation linkages has a negative relationship with the ease in which different citers evaluate prior art in the same way, thereby providing a new perspective on the notion of breadth in citation impact.


Examiner citation X/Y citations DOCDB patent family Family-to-family citations Blocking patents Trilateral offices Triadic patent 

Mathematics Subject Classification


JEL Classification

K29 O33 O34 



The present study is an extended version of an article presented at the 16th International Conference on Scientometrics and Informetrics, Wuhan (China), 16–20 October 2017 (Wada 2017). This study was conducted as a part of a project for the Research Institute of Science and Technology for Society (RISTEX) and the Japan Science and Technology Agency (JST). This study also benefited from a research project, “Study on Industrial Innovation Capability and Innovation Infrastructure,” undertaken at the Research Institute of Economy, Trade and Industry (RIETI). The author is grateful for helpful comments and support from Setsuko Asami, Stuart Graham, Alan Marco, Sadao Nagaoka, Yoshimi Okada, Alfons Palangkaraya, Andrew Toole, the seminar participants at RIETI, and the audience at the 12th Annual Conference of the European Policy for Intellectual Property (EPIP).


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2018

Authors and Affiliations

  1. 1.Faculty of EconomicsGakushuin UniversityTokyoJapan

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