When crafting an appeal brief, even a seemingly minor detail can become a stumbling block. In previous posts on www.mriplaw.com, we have discussed how the PTAB scrutinizes your specification to ensure that your arguments remain consistent with the record—even if the examiner didn’t initially raise any such issues. Today, we focus on another subtle trap: dependent claims and the doctrine of claim differentiation ruining arguments about the scope of an independent claim relative to the cited art.
On appeal, applicants often contend that the independent claims exclude, or do not extend to cover, certain features present in the cited art. The strategy is straightforward: by arguing that the independent claim does not cover a specific feature, the cited art is distinguished and the rejection should be reversed. However, in making such arguments, applicants should be careful that a dependent claim related to the disputed scope does not explicitly incorporate (or exclude) that very feature. When it does, this may open the door for the Board to invoke the doctrine of claim differentiation to find that the independent claims is generic to whether that feature is included, or excluded, thus making the independent claim scope broad enough to encompass it. In essence, there can be situations where the dependent claim is interpreted as evidence that the independent claim was drafted with a broader scope with respect to the disputed feature.
Consider a recent PTAB appeal as to an invention related to luggage by Samsonite. Application 16/493,442. Specifically, the application relates to “the use of laminated biaxially oriented thermoplastic polymer films in the construction of the shell structure of a luggage case.” As explained by the PTAB:
The Specification teaches that hard-side luggage is conventionally known but conventionally used materials “are difficult to manufacture and mold.” Id. ¶ 2. The inventors seek to remedy such problems and, additionally, “provide[ ] an improved plastic laminate material that is lightweight and impact resistant.” Id. ¶ 6. The Specification teaches that a luggage shell may be formed of a laminate of a plurality of coextruded films where the films include a core of a biaxially oriented thermoplastic polymer and at least one outer layer of a thermoplastic polymer. Id. ¶ 6.
Independent claim 1 is representative of the claims and is reproduced
below.
1. A luggage shell comprising:
a shell formed of a laminate of a plurality of coextruded films, each of the films comprising:
a core of a biaxially oriented thermoplastic polymer, and
at least one outer layer of a thermoplastic polymer, the outer layer having a thickness of 0.5% to 25% of the thickness of the respective film.
Samsonite argued that the cited prior art was deficient because it disclosed materials that are woven prior to taking a final form and therefore outside the scope of claim 1 requiring “a shell formed of a laminate of a plurality of coextruded films.”
Rather than tackling the technical aspects of this argument, the specific claim language of claim 1, and the particular teachings of the cited art, the PTAB turned to dependent claim 24 (in fact the applicant actually brought up claim 24 in the oral hearing as support for the idea that claim 1 did not cover woven films). Claim 24 depended from claim 1 and specified that the “the plurality of coextruded films are non-woven films.”
At first, claim 24 might be considered clear evidence that claim 1 also should not extend to cover non-woven films. But in reality, the opposite occurred. The PTAB merely followed a straightforward application of claim differentiation to find that claim 1 could not be limited to non-woven films because claim 24 limited the scope to such non-woven films. Claim 1 must therefore, according to the doctrine, be broad enough to cover more - namely, woven films. The PTAB previewed this argument in the oral hearing as well, to which the applicant responded as follows:
An interesting point. I think I would go back to that when [the cited prior art] describes films we have to look at not just that [it] uses the word film. We have to look at the whole reference and that [it] is describing processing of films into strips or tapes and that's not what we're describing.
The PTAB was not convinced. From the decision:
Under the doctrine of claim differentiation, “the presence of a dependent claim that adds a particular limitation gives rise to a presumption that the limitation in question is not present in the independent claim.” Phillips v. AWH Corp., 415 F.3d 1303, 1315 (Fed. Cir. 2005). Applying the doctrine of claim differentiation, and according claim 1 its broadest reasonable interpretation, we determine that the “shell formed of a laminate” of claim 1 would include a shell formed of woven laminate.
The PTAB followed such reasoning even though neither the applicant, nor the examiner, raised the issue of claim 24 or the doctrine of claim differentiation.
But then one would think that by this logic, the PTAB would not be able to sustain the rejection of claim 24 (as claim 24 now expressly proscribed the cited prior art. Not so - because Samsonite did not separately argue claim 24 (which is required by the appeal rules), the PTAB did not have to address claim 24 as any arguments not made in the brief are waived.
To reduce the chances of having your scope arguments undermined by dependent claims, consider the following tips when drafting your appeal brief:
Conduct a Thorough Claim Analysis
Review all claims—both independent and dependent and even those not being argued—to identify any that might inadvertently be inconsistent with positions for the argued claims. Understand how each claim interacts with argued claims, and where potential conflicts may arise.Address Dependent Claims Expressly
If a dependent claim potentially better distinguishes the cited art, consider a separate argument for that claim, and do so considering how the independent claim argument may be lost.Preempt the Claim Differentiation Argument
If a claim differentiation issue might impact your arguments, consider addressing it head-on. Clearly articulate how the dependent claim distinguishes other aspects and it not coterminous with the material to be included/excluded.Ensure Consistency with the Specification
As highlighted in earlier posts, the PTAB will closely review your specification on appeal, even if the examiner did not. Make sure your arguments about claim scope are firmly grounded in and consistent with the disclosure in the specification.
Dependent claims can be a double-edged sword on appeal. When not properly considered, they may undermine well-crafted arguments about claim scope, allowing the Board to sustain rejections based on prior art of not only the independent claims, but also the dependent claim. A proactive and holistic approach in the appeal brief can strengthen your chances for success and make it more difficult for the PTAB to sidestep real issues in the case.