Ex parte Spangler: Written Description Requirement Satisfied by Single Embodiment in the Specification

In a recent appeal of a rejection based on the written description requirement, the Patent Trial and Appeal Board (the “Board”) found a claimed invention directed to a featherseal structure to be sufficiently supported by the illustration of a single embodiment in the specification.¹ Under the written description requirement of 35 U.S.C. § 112(a) or § 112, first paragraph (pre-AIA), a patent claim can be challenged on the basis that its corresponding specification does not describe enough embodiments or structural features to support the full scope of the claim. ² The determination of whether the patent claim is sufficiently supported by the specification is a fact-based inquiry that depends on the nature of the invention being claimed. ³

The rejection in the case relates to an application⁴ for a featherseal that engages a turbine engine component. ⁵ The application includes a figure (Figure 3, reproduced herein) that depicts a featherseal 76 that has a first tab 80 and a second tab 86 that are plugged into a slot 86. ⁶ The first tab 80 and the second tab 82 prevent the featherseal 76 from moving side to side once it is plugged into the slot 86. ⁷

During prosecution, the applicant attempted to amend the claims to recite a first lateral tab that has a different length than a second lateral tab. ⁸ The applicant contended that the claim amendment is supported by Figure 3, which shows the first tab 80 having a smaller length than the second tab 82. ⁹ The Examiner disagreed and rejected the claim amendment as failing to comply with the written description requirement. The Examiner asserted that the single embodiment illustrated in Figure 3 does not support the full scope of the claim amendment. ¹⁰ The full scope of the claim amendment covers a first embodiment in which a first tab is shorter than a second tab, as well as a second embodiment in which the first tab is longer than the second tab. ¹¹ The Examiner acknowledged that Figure 3 of the specification discloses the first embodiment, but found no support in the specification for the second embodiment. ¹² Thus, according to the Examiner, because the second embodiment is not disclosed, the full scope of the claim is not supported by the specification. ¹³

The Board reversed the rejection. It agreed with the applicant that “the disclosure of one embodiment [in figure 3] wherein the forward tab has a different (i.e., smaller) length than the aft tab and wherein the forward slot opening has a different (i.e., smaller) length than the aft slot opening is sufficient to provide support for the claim limitations in question.”¹⁴ The Board reached this conclusion “notwithstanding that the claim limitations . . . also cover another embodiment (i.e., the forward tab having a larger length than the aft tab and the forward opening having a larger length than the aft opening) not specifically disclosed in the application.”¹⁵ .” It reasoned that the specification “does not specifically address the relative lengths of the first and second tabs or the first and second openings.”¹⁶ Further, the specification “gives no indication that the specific arrangement illustrated (i.e., the forward tab and opening having shorter lengths than the aft tab and opening) is critical to the invention or is the only possible arrangement for the tabs and openings.” ¹⁷ In other words, “the original disclosure in the present application does not restrict the scope of the invention to the forward tab and opening having smaller lengths than the aft tab and opening.” Id. Based on this reasoning, the Board found the claim amendment to be sufficiently supported by the specification.

The Board’s reasoning in Ex parte Spangler may be useful in cases where an Examiner rejects a claimed structure as being too broad compared to what is disclosed in specification. The Board in this case concluded that the claim amendment should not be limited to the disclosed structure in the specification partially because there was no indication that the disclosed structure is critical, or is the only possible arrangement for the claimed featherseal. Many other applications may similarly disclose details that enhance a particular structure, but may not indicate that those details are critical or are the only possible arrangement for the structure. In such situations, the reasoning in Ex parte Spangler may help to address a rejection based on lack of written description.