by Dennis Crouch
Although our attention over the past few years has focused more on eligibility and definiteness issues, claim construction continues to befuddle the courts. In MultiLayer Stretch Cling Film v. Berry Plastics (Fed. Cir. 2016), the Federal Circuit has offered a split interpretation of the patent’s Markush group claim element.
The asserted cling-film claim requires “five identifiable inner layers with each layer being selected from the group consisting of LLDPE, VLDPE, ULDPE, and mLLDPE resins.”
The accused products include inner layers made of a different resin (not listed in the claim) and also layers with blends of the above listed resins. In claim-construction mode, the court found that the claim would not extend to these embodiments. The court particularly focused on the “consisting of” language used in defining the group and noted that a broader approach would have written “comprising.”
What is critical here is that the transitional phrase . . . “consisting of,” is a term of art in patent law with a distinct and well-established meaning. Use of the transitional phrase “consisting of” to set off a patent claim element creates a very strong presumption that that claim element is “closed” and therefore “exclude[s] any elements, steps, or ingredients not specified in the claim.” . . . Thus, if a patent claim recites “a member selected from the group consisting of A, B, and C,” the “member” is presumed to be closed to alternative ingredients D, E, and F. By contrast, the alternative transitional term “‘comprising’ creates a presumption that the recited elements are only a part of the device, that the claim does not exclude additional, unrecited elements.”
The majority agreed with the dissent that elements of the specification as well as other claims suggest that the broader invention includes other non-listed resins. However, the majority and dissent disagreed on the impact of those alternative facts.
We do not think that the listing of these other resins in the specification is sufficient to overcome the presumption created by the “consisting of” claim language. . . . [Further], ‘[t]he dependent claim tail cannot wag the independent claim dog.’
I think that this is a close call, but I would conclude that the claim language is not so plain.
The dissent’s textual argument is that, although “layer consisting of [listed resins]” would have been clear, that clarity was muddied by the patentee’s more complex “layer being selected from the group consisting of [listed resins].” The actual claim language leaves “semantic uncertainty” that then opens the door to more consideration of the specification and claim differentiation.