Chapter §6.01 The Varied Meanings of "Written Description"

• Jurisdiction: United States

§6.01 The Varied Meanings of "Written Description"

The most controversial and opaque of the three disclosure requirements derived from the first paragraph of 35 U.S.C. §112 is the requirement that a patent's specification must contain a written description of the invention.¹ The Federal Circuit has vigorously applied the written description requirement as a tool for limiting the scope of patents, particularly those claiming chemical and biotechnological inventions.² One Federal Circuit judge has described the court's written description jurisprudence as "a wildcard on which the court may rely when it faces a patent that it feels is unworthy of protection."³ Another observes that "district courts and practitioners . . . are currently left to trudge through a thicket of written description jurisprudence that provides no conclusive answers and encourages a shotgun approach to litigation."⁴

Before exploring the details of the requirement, it should be clarified that U.S. patent law uses the phrase "written description" in at least two ways. In its more pedestrian sense, "written description" simply refers to a physical part of the patent specification. The written description portion of a patent encompasses all of the document's content other than the drawings and claims (that is, the written description includes those sections of the patent specification that are typically labeled "Background of the Invention," "Summary of the Invention," and "Detailed Description of the Invention").⁵

In another sense, the phrase "written description" is a shorthand reference to a disclosure requirement that the patent's specification must satisfy in accordance with the first paragraph of 35 U.S.C. §112. As explained below, the traditional view of this legal requirement was that the language of patent claims which an applicant newly presented or amended after the filing date of her application had to find adequate "support" in the application as it was originally filed. The written description of the invention requirement was applied to these time-gap situations in which an applicant was claiming priority for later-presented claims back to an earlier application filing date.

Starting in 1997 with Regents of the Univ. of California v. Eli Lilly & Co.,⁶ a line of Federal Circuit decisions has expanded the scope of the written description of the invention doctrine far beyond its traditional, relatively limited purview as a priority policing tool.⁷ As described below, the court now uses the written description of the invention requirement as a means of cabining the scope of originally-filed claims (i.e., claims included in a patent application when first filed), particularly those claims reciting a genus of chemical or biotechnological compounds.⁸

In attempting to clearly differentiate these two uses of the phrase "written description," this treatise will generally refer to the disclosure requirement by its full statutory...