Invalidated Patents and Associated Patent Examiners

Shine Tu · 18 Vand. J. Ent. & Tech. 1


This study attempts to determine whether there are common characteristics between examiners who issue invalidated patents. This study uses two new patent databases that code for nearly 1.7 million patents and approximately one thousand patents that were litigated to a “final” judgment between 2010 and 2011. This study finds that approximately one-third of patents that are litigated to final judgment are found invalid. Most invalidated patents are found in technology centers 1600, 2600, and 2700, which correspond to biotechnology and organic chemistry, communications, and computer science, respectively. Most patents are invalidated on prior art-type novelty and obviousness grounds. This study also determined that: (1) litigated patents mainly come from primary examiners (those examiners with more experience), and (2) primary examiners that grant between thirty and sixty patents per year are issuing a higher number of invalidated patents. Interestingly, the highest volume primary examiners (examiners who on average grant more than one hundred patents per year and have more than seven years of experience) issue very few litigated patents that are later found invalid. Most of the patents that were invalidated in this data set were done so via the prior art language of 35 U.S.C. §§ 102–103. Approximately 77 percent of the prior art references used to invalidate patents were not found by the US Patent and Trademark Office (USPTO) during examination. Additionally, 38 percent of the prior art references used to invalidate patents were US patents or US patent applications. Of those invalidating references that were US patents or patent applications, approximately 89 percent were not found by the examiner. These data imply that improving PTO searching could improve patent quality.