It is a long-standing rule that if you want to claim the benefit of an earlier filing date, the earlier filed application must provide a written description of the later claim. This can get sticky where the earlier filing discloses a species and you later want to claim a genus, or vice versa. This issue was squarely presented in Hologic Inc. v. Smith & Nephew Inc. — an appeal from an Inter Partes Re-examination — and decided in favor of the patentee.

Smith & Nephew’s (S&N) patent claimed the benefit of an earlier Patent Cooperation Treaty (PCT) application. The PCT application disclosed fiber optic cable running between a light source and a lens. In a divisional application filed off of the U.S. national phase entry from the PCT, S&N amended the claims to require a “first channel having a light guide permanently affixed therein.” The words “light guide” never appear in the PCT application, so Hologic raised a grounds for rejection in Inter Partes Re-examination based on the idea that the PCT publication is prior art against the claims, rather than a priority document supporting the claims. In other words, Hologic was arguing that disclosure of a species (fiber optic cable) is not enough to support a later claim to a genus (“light guide”).

The Examiner agreed with Hologic, but the Patent Trial and Appeal Board (PTAB) reversed and held for S&N. The PTAB reasoned that the person of ordinary skill is broadly familiar with a host of similar medical device, including devices that use either removable or permanently affixed light guides, and that mechanical devices such as the one claimed here are part of a “predictable” art. Therefore, the PTAB considered that disclosure of one such light guide (fiber optic cable) is enough to convince the skilled reader that the inventors had possession of devices using other known light guides.

The Federal Circuit agreed with the PTAB. Written description support is a question of fact, reviewed under the deferential “substantial evidence” standard. The Federal Circuit was easily convinced that the PTAB’s decisions about the various fact issues (are light guides well known in the art? are mechanical devices part of a predictable art field? is a fiber optic cable a species of the genus “light guide”?) were supported by substantial evidence.

S&N had provided expert declarations to the effect that a skilled reader would recognize from the drawings that the illustrated fiber optics are permanently affixed and not removable. This declaration evidence provided support on which the Federal Circuit could rely to show that the PTAB’s fact findings were supported by substantial evidence.

The take-home conclusion of this case is that — at least where an invention arises in a “predictable” art field such as mechanical devices or electronics — disclosure of even a single species can be enough to support a later claim to a genus. This is not to say, however, that you can disclose a frog and later claim “green things.” It helped here that the genus “light guide” is not vastly larger than fiber optics. Still, where the art field is predictable and the appropriate expert declarations are provided to explain the knowledge that a skilled reader brings to the reading of your earlier filing, a species disclosure can support a genus claim.