Patenting Fast and Slow: Examiner Rejections and Applicant Traversals to Non-Prior Art Rejections

39 Pages Posted: 2 Mar 2020

See all articles by Shine (Sean) Tu

Shine (Sean) Tu

West Virginia University College of Law

Date Written: March 1, 2020


It is no secret that some Patent and Trademark Office (PTO) examiners operate more quickly than others. Previous studies have shown that an applicant’s ability to obtain a patent is inexorably linked to the random assignment of a patent examiner. However, not all patent examiners are created equal. Some patent examiners allow patent applications quickly within just one or two Office Actions resulting in only a few months of substantive patent prosecution. In contrast, other patent examiners constantly reject patents applications, which can result in unnecessarily delaying prosecution and years of substantive patent prosecution. This study focuses on how different examiners use prior art rejections to prolong or compact prosecution.

This study demonstrates how two different populations of patent examiners (slow vs. fast) can achieve and even exceed their production goals by either an allowance or rejection strategy. The allowance strategy relies on granting a large number of applications with only a few rejections and usually within one or two office actions. The rejection strategy relies on rejecting a large number of applications using a wide variety of different rejection types. Unlike many studies, this is the first paper that evaluates patent quality based on individual examiner characteristics at the patent prosecution level focused on non-prior art rejections.

In particular, high volume biotechnology examiners reject applications based mainly on obviousness type double patenting and indefiniteness rejections, while issuing fewer obviousness or anticipation type rejections. In contrast, low volume examiners reject applications based mainly on obviousness rejections. Furthermore, number of pages in the low volume examiners’ office actions are more than three times more than high volume examiners. Thus, low volume examiners are writing longer office actions and rejecting based on a wide variety of statutory authorities, while high volume examiners are writing shorter office actions based mainly on obviousness type double patenting issues.

We find that different types of examiners use different strategies to maximize their “counts” in order to keep their production numbers high. Specifically, low volume examiners will generally reject applications creating lengthy prosecution histories while forcing the applicant to narrow claims. In contrast, high volume examiners will usually only make one rejection then allow the case, thus creating a small prosecution history with only small amendments to the claims. This results in a dramatic range of patent prosecution times as well as a large difference in claim scope. Slow examiners take approximately 5.85 years to issue a patent while fast examiner only take approximately 1.64 years. The added four years of prosecution greatly increases direct costs to the inventor (both in PTO and attorney fees) as well as indirect costs such as reduced growth in employment, sales and follow on innovation. Finally, there may be harms to not only the inventor, but to rivals in the form of diminished access to external capital and slower growth of follow on innovation.

Keywords: patents, patent examiner, patent prosecution, prior art, prior art rejections, patent quality, applicant response, applicant behavior, PTO, empirical

JEL Classification: K10

Suggested Citation

Tu, Shine (Sean), Patenting Fast and Slow: Examiner Rejections and Applicant Traversals to Non-Prior Art Rejections (March 1, 2020). WVU College of Law Research Paper No. 2020-005, Available at SSRN: or

Shine (Sean) Tu (Contact Author)

West Virginia University College of Law ( email )

101 Law School Drive
Morgantown, WV West Virginia 26506
United States

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