Written Description Required to Claim Priority from a PCT

The Federal Circuit has clarified what written description is sufficient for a PCT application to qualify as a priority document for a U.S. Patent application. In Hologic, Inc. v. Smith & Nephew, Inc., No. 2017-1389 (Fed. Cir. Mar. 14, 2018) the Federal Circuit upheld a Patent Trial and Appeal Board (PTAB) decision finding that an earlier-filed PCT application (Publication No. WO 99/11184) provided sufficient written description to qualify as a priority document for U.S. Patent No. 8,061,359 under 35 U.S.C. §§ 112 and 120.

The ‘359 patent is directed to an endoscope and is owned by Appellee Smith. The ‘359 patent issued from a divisional application of the national stage of the ‘184 PCT. The specification of ‘359 patent as originally filed and the ‘184 PCT application were nearly identical. The claims in the ‘359 patent recite a “light guide.” During prosecution of the ‘359 patent the Examiner objected to the drawings for failing to show the light guide. The specification was then amended during prosecution to state “[a] connection 8 for a light source is also present, for connection to a light guide, such as a fibre optics bundle which provides for lighting at the end of lens 13.” (Language added during prosecution is underlined.).

Appellant Hologic initiated an inter partes reexamination of the ‘359 patent challenging the availably of the ‘184 PCT as a priority document. Hologic alleged that the ‘184 PCT does not have sufficient written description for the recited claim elements of “the first channel having a light guide permanently affixed therein.” The Examiner for the reexamination found that ’184 PCT did not have sufficient written description to be a priority document. Smith appealed the Examiner’s decision to the PTAB. The PTAB reversed, and held that there is sufficient written description in the ‘184 PCT to provide priority to the claimed elements. If the ‘184 PCT had been found to have inadequate written description it would have be an invalidating piece of prior art under 35 U.S.C. §§ 102 and 103.

The standard for determining whether there is sufficient written description under 35 U.S.C. § 112 is based on “an objective inquiry into the four corners of the specification from the perspective of a person of ordinary skill in the art  …, the specification must describe an invention understandable to that skilled artisan and show that the inventor actually invented the invention claimed.” Ariad Pharm., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc). To meet this burden, the PTAB found, and the Federal Circuit here agreed, that a “field of the invention” was a “predictable art,” such that a lower level of detail is required to satisfy the written description requirement than for unpredictable arts.

In affirming the PTAB decision, the Federal Circuit first looked at whether the initial disclosure of a “fibre optics bundle” provided disclosure of a broader “light guide.” The Federal Circuit noted that the parties did not dispute that a “fibre optic bundle” is a type of “light guide,” and that various types of light guides were well known in the art. Next, the Federal Circuit looked to whether a “first channel” was sufficiently disclosed, and found that a person of ordinary skill would understand the “light channel” or “viewing channel,” labeled as element 6 in the ‘184 PCT drawings, as providing such disclosure. Finally, the Federal Circuit looked to whether there was sufficient written description of a “light guide permanently affixed therein.” (emphasis added). To resolve this issue, the Federal Circuit looked to the ‘184 PCT which showed that “viewing channel 6 is bookended by lens 13 and viewing tube 7 is evidence that these components form a unitary part that is not removable.”

The court went on to discuss extrinsic evidence, namely patents for other endoscopes and expert testimony indicating that endoscopes come in two types: a removable “telescope,” or a unitary integrated device, which are distinguishable merely by looking a pictures of the devices. The expert testimony concluded that the ‘184 PCT illustrated permanently affixed light guides and lenses, similar to those shown in other pieces of prior art.

Hologic unsuccessfully argued that the PTAB improperly relied on the prior art to provide disclosure of claim elements. The Federal Circuit disagreed, stating that the PTAB simply considered what the specification reasonably conveys to the skilled artisan who has knowledge of the prior art. To put it another way, the prior art was used by the PTAB to aid in determining what a person of ordinal skill in the art would understand from the ‘184 PCT if that person also had knowledge of such prior art.

Lessons for Practice

Key to this case was the classification of the disclosed field of the invention as a “predictable art,” allowing the broader genus to be disclosed by the originally disclosed species. Also key to this case was the use of prior art to show what would be understood by a person having ordinary skill in the art. In particular, the use of prior art to show that the claimed device was known as having only two types, and that claim language in dispute was merely indicating one of those two types.

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