The broadest-construction rubric coupled with the term “comprising” does not give the PTO an unfettered license to interpret claims to embrace anything remotely related to the claimed invention.Details: I'll focus only on the claim construction of "material for finishing." Full details of the case can be found here on the 37 Thoughts blog.
The claim at issue was:
4. On a floor having a flat top surface and an improved material for finishing the top surface of the floor, the improvement comprising:
at least one elongated sheet including a uniform flexible film ... and
a continuous layer of adhesive material disposed between the top surface of the floor and the flexible film, the adhesive layer releasably adhering the flexible film onto the top surface of the floor.
The BPAI interpreted "material for finishing" as "a material that is structurally suitable for placement on the top surface of a floor." The BPAI also relied on the transitional phrase "comprising" to allow "the finishing material to fall anywhere above the surface being finished regardless of whether it actually ‘finishes’ the surface."
The court disagreed and found that the "material for finishing" is the "layer on the top surface of a floor that is the final treatment or coating of a surface," explaining that:
A material cannot be finishing any surface unless it is the final layer on that surface. Otherwise, the material would not be “finishing” the surface in any meaningful sense of the word.The court remanded to the BPAI for a new invalidity analysis with the proper claim construction.
My two cents: I see the holding of In re Suitco as: while "comprising" allows additional elements, it does not allow for the presence of additional that overrule an explicit limitation. In Suitco, additional layers on top of the finishing material were not allowed because such layers would overrule the "material for finishing" limitation.
The BPAI has twice used In re Suitco in precisely this manner to reject an Examiner's interpretation that included elements excluded by the claim. Ex parte Henninge involved a lithium battery, with the claim limitation at issue being "wherein the separator-electrode unit comprises an inorganic separator unit." The Examiner argued that because "comprising" was used as the transitional phrase, the separator-electrode unit could include organic ingredients. The BPAI rejected this interpretation because the claim contained an explicit requirement that the separator is inorganic.
Ex parte Wu was a chemical case, where the claim limitation at issue was “one or more carbon black fillers, wherein said fillers are the only fillers in the organosilane masterbatch.” The Examiner used a reference which taught silica (not carbon black) fillers, and argued that this met the claimed limitations because "the term 'comprising' permits inclusion of the additional ingredients not recited in the claims." The Board rejected this interpretation, finding that "['comprising'] does not permit the presence of those fillers, including silica fillers, which are specifically excluded by the explicit language of the claims."