Chapter §6.05 Written Description Versus Enablement

• Jurisdiction: United States

§6.05 Written Description Versus Enablement

As interpreted and applied by the Federal Circuit, the written description of the invention requirement stands apart from the enablement requirement. Commentators identify the CCPA's 1967 decision in In re Ruschig⁷⁹ as the first express identification of a written description of the invention requirement that is doctrinally separate from the enablement requirement.⁸⁰

The Ruschig appeal involved the patentability of a single claim directed to a chemical compound known generically as chlorpropamide, a drug used to treat diabetes.⁸¹ Claim 13 was added to Ruschig's patent application after a USPTO examiner suggested it for the purpose of provoking an interference with another applicant, about a year after the application's filing date. The USPTO rejected the claim because "[t]he compound of claim 13 is not named or identified by formula and it can find support only as choices made between the several variables involved. This is not regarded as adequate support for a specific compound never named or otherwise exemplified in the specification as filed."⁸²

In an opinion authored by Judge Giles Rich, the CCPA affirmed the USPTO's rejection of the claim. It was not disputed that the application as filed disclosed a chemical genus encompassing about half a million possible compounds, as well as disclosing a number of specific compounds. Ruschig argued that this disclosure contained certain "guides" that would lead one of ordinary skill to the particular compound of claim 13. The CCPA did not agree, using a now-famous metaphor to illustrate the problem with the original application:

It is an old custom in the woods to mark trails by making blaze marks on the trees. It is no help in finding a trail or in finding one's way through the woods where the trails have disappeared-or have not yet been made, which is more like the case here-to be confronted simply by a large number of unmarked trees. Appellants are pointing to trees. We are looking for blaze marks which single out particular trees. We see none. ⁸³

Ruschig also argued that his application as filed was enabling. The CCPA clarified that the issue before it was not enablement, but rather whether the original application adequately described the invention recited in the later-filed claim:

Appellants refer to 35 U.S.C. §112 as the presumed basis for this rejection and emphasize language therein about enabling one skilled in the art to make the invention, arguing therefrom that one skilled in the art would be enabled by the specification to make chlorpropamide. We find the argument unpersuasive for two reasons. First, it presumes some motivation for wanting to make the compound in preference to others. While we have no doubt a person so motivated would be enabled by the specification to make it, this is beside

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