A vs The: Preamble Limitations

by Dennis Crouch

Shoes by Firebug LLC v. Stride Rite Children’s Group (Fed. Cir. 2020) petition for rehearing denied (Fed. Cir. August 12, 2020).

The Federal Circuit originally decided this claim construction case in June 2020 on the topic of when a claim preamble is limiting. The court has now denied Firebug’s petition for rehearing.

The case is interesting because it involves two Firebug patents with identical claim preambles. On appeal the Federal Circuit found one preamble limiting, and the other non-limiting. The result here shows that (1) this continues to be a tricky issue; and (2) whether a preamble is limiting is substantially determined by the body of the claim (rather than simply an examination of the preamble itself).

The preamble at issue: “1. An internally illuminated textile footwear comprises.” U.S. Patents 8,992,038 and 9,301,574.  The prior art internally illuminates a piece of plastic that is part of the shoe upper, and the patentee argues that its claims require the textile itself to be internally illuminated. The problem for the patentee is that the limitations in the claim body do not expressly require light diffusion through the textile — hence its reliance on the preamble.

Construction of a claim preamble is a holistic process and requires “review of the entire patent” with any particular litmus test. Coning Glass.  The court has offered a number of platitudes regarding claim preamble limitations — like most platitudes, these are rarely sufficient resolve any particular dispute.

• Limiting: recites essential structure or steps.
• Limiting: necessary to give life, meaning, and vitality to the claim.
• Limiting: reliance on preamble phrase for antecedent basis.
• Not Limiting: body of the claim defines a structurally complete invention.
• Not Limiting: preamble merely states a purpose or intended use for the invention.

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The two patents at issue share the same (almost the same) specification and the claims are also quite similar.  The table above shows the most relevant portion of the two claims.  As mentioned, the during the IPR, the patentee wanted the claims to be construed to require that the textile be internally illuminated.

In distinguishing between these two claims, the court basically put on its simplistic grammar hat. The preamble recites a “footwear”, but the ‘038 claim body reintroduces “a footwear” while the ‘574 claim body’s first reference is to “the footwear.”

The preamble [of the ‘038 claim] cannot be said to provide essential structure or necessary meaning to the claimed invention because the same element—the footwear—is independently recited in the body of the claim. . .

Unlike claim 1 of the ’038 patent, claim 1 of the ’574 patent does not reintroduce “footwear” in the body of the claim but instead relies on the instance of “footwear” introduced in the preamble for “antecedent basis.” . . . Because the claim requires that the illumination system be housed in the textile footwear recited in the preamble, the preamble is essential to understanding the structural limitations of the illumination system. Accordingly, rather than merely reciting an intended purpose of the claimed invention, we conclude that the preamble of claim 1 of the ’574 patent limits the scope of claims 1–10 of the ’574 patent to require the use of a textile upper

Slip Op.  Despite its strong reliance on “a” vs “the”, the court reiterated that the process is holistic and noted that nothing in the specification or prosecution history demanded that the light pass through a textile.

Still Obvious: Although the patentee got its limiting construction for the ‘574 patent, the Federal Circuit still affirmed the obviousness determination. Basically, the PTAB had offered an “alternative fact finding” that the prior art “suggests using a woven, porous material in a light diffusing, internally illuminated part of footwear”, and the court affirmed that finding as based upon substantial evidence.

The patentee petitioned for rehearing with a seemingly important argument.  The Board’s “alternative fact finding” was written in an aside within FN16 of the Final Written Decision.  Firebug argues that the conclusion was introduced for the first time in the final written decision and “Firebug did not have the opportunity to address” the issue.   The petition has now been denied without new opinion.

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Firebug also argued secondary indicia of nonobviousness. In particular, the patentee presented two third-party license agreements for the patents at issue as well as testimony of Ralph Shanks who negotiated one of the licenses (against Firebug). On appeal, the Federal Circuit noted that the licenses included “eight patents, two patent applications, and one trademark.”  The court questioned the nexus to the particular invention here, but affirmed on the ground that the evidence is so weak that even if a nexus exists the claims are still obvious.  An odd bit of the decision is that the conclusion of “weakness” appears to be directly tied to the no-nexus argument that was not affirmed.