An Empirical Study of the Role of the Written Description Requirement in Patent Prosecution

16 Pages Posted: 22 Feb 2010 Last revised: 6 Dec 2014

Date Written: February 18, 2010


An en banc Federal Circuit is now considering whether Section 112 of the Patent Act as properly interpreted includes a written description requirement that is separate and distinct from the enablement requirement. Although the USPTO has no direct role in the infringement dispute, the government submitted an amicus curie brief arguing that a separate written description requirement is “necessary to permit the USPTO to perform its basic examination function.” However, when pressed during oral arguments the government could not point to any direct evidence supporting its contention.

This essay presents the results of a retrospective empirical study of the role of the written description requirement in patent office practice. It is narrowly focused on rebutting the USPTO’s claim that the separate written description requirement serves an important role in the patent examination process. To the contrary, my results support the conclusion suggested by Chief Judge Michel that it is indeed “exceedingly rare that the patent office hangs its case on written description.”

For the study, I analyzed 2858 Board of Patent Appeals and Interference (BPAI) patent opinions decided January-June 2009. Written description issues were decided in 123 (4.3%) of the decisions in my sample. Perhaps surprisingly, I found that none of the outcomes of those decisions would have been impacted by a legal change that entirely eliminated the written description requirement of Section 112 so long as the USPTO would still be allowed to reject claims based on the addition of “new matter” (perhaps under 35 U.S.C. Section 132). New-matter style written description requirement rejections were outcome determinative in 20 of the 2858 cases – about 1.0% of the cases in my sample.

Although there may be valid reasons for retaining a separate written description requirement, this study safely leads to the conclusion that the government’s conclusory statements regarding the doctrine's critical importance for patent examination lack a factual basis.

Keywords: patent, patents, patent prosecution, written description, Section 112, BPAI, Patent Appeals

Suggested Citation

Crouch, Dennis D., An Empirical Study of the Role of the Written Description Requirement in Patent Prosecution (February 18, 2010). Northwestern University Law Review Colloquy, Vol. 104, 2010, University of Missouri School of Law Legal Studies Research Paper No. 2010-06, Available at SSRN:

Dennis D. Crouch (Contact Author)

University of Missouri School of Law ( email )

Missouri Avenue & Conley Avenue
Columbia, MO MO 65211
United States

Do you have negative results from your research you’d like to share?

Paper statistics

Abstract Views
PlumX Metrics