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IP Alert: Federal Circuit Issues Critical Guidance on Markush Claiming

August 8, 2016

On August 4, 2016, the U.S. Court of Appeals for the Federal Circuit issued a split panel decision in Multilayer Stretch Cling Film Holdings, Inc. v. Berry Plastics Corporation. The court held that a claimed structure “selected from the group consisting” of alternatives A, B, C, and D did not cover a structure containing alternative E. The court further held that based on the intrinsic record of the patent at issue, the claim did cover a structure containing blends of A, B, C, or D, despite the absence of language specifying that mixtures were permitted. This decision is essential reading for those drafting, asserting, or defending against patents that contain Markush-format claims.

Multilayer Stretch Cling Film Holdings, Inc. (“Multilayer”) is the owner of U.S. Patent No. 6,265,055. The ’055 patent is directed generally to a multilayered stretch cling film for commercial packaging. Multilayer sued Berry Plastics Corporation (“Berry”), alleging infringement.

The independent claims of the ’055 patent specify layered polymeric films, “each layer being selected from the group consisting of [alternatives A, B, C, and D].” The alternatives include four types of polyethylene resins, namely, the resins LLDPE, VLDPE, ULDPE, and mLLDPE. Dependent claim 10 purports to recite that at least one of the layers comprises a fifth alternative E, the resin LDPE. Dependent claim 24 recites that the layer is composed of a blend of at least two resins.

The district court construed the independent claims to mean that each inner layer must contain only one of the listed classes of resins A, B, C, or D, and no other resins. It was undisputed that at least one of the inner layers of Berry’s films included blends of alternatives A+C+D, and, based on its claim construction, the district court granted summary judgment of non-infringement to Berry. Also, because claim 10 purported to allow a fifth resin, E, the district court held the claim to be invalid under 35 U.S.C. § 112(d) as improperly broadening the scope of claim 1. The district court rejected Multilayer’s contention that claim 10 signified that claim 1 was open to additional resins.

On appeal, the Federal Circuit began by noting that the issues raised by the parties were issues of claim construction, to be reviewed de novo. The court further noted the parties’ agreement that the independent claims were of the Markush format.

The majority opinion stated that use of the transitional phrase “consisting of” in a Markush group creates a very strong presumption that the claim element is “closed” so as to exclude subject matter not specified in the claim, and the presumption may be overcome only if the specification and prosecution history “unmistakably manifest an alternative meaning” for the transitional phrase. Multilayer argued that the specification clearly demonstrated an intent for the independent claims to be open to other unlisted resins. To support this argument, Multilayer pointed to claim 10 reciting alternative E, and the disclosure in the specification of other resins that are not listed in the Markush group.

The court was not persuaded, holding that the disclosure in the specification of alternative resins that may be used in an inner layer but that were not listed in the independent claims did not overcome the strong presumption established by the use of the phrase “consisting of.” Similarly, the court was unconvinced that the recitations in claim 10 overcame the presumption. The court reasoned that while a dependent claim can be useful for interpreting the recitations of an independent claim from which it depends, the language of a dependent claim cannot change the scope of an independent claim whose meaning is clear on its face. Based on this reasoning, the court affirmed the district court’s construction of the Markush group as excluding unlisted resins, and also affirmed the invalidity of claim 10.

Turning next to the question of whether the claim allowed for mixtures of the resins A, B, C, and D, the court observed that a Markush group that does not include language regarding mixtures of the listed components creates a presumption that the group is closed to mixtures. Notably, the court stated that the simple inclusion of language such as “and mixtures thereof” would have been sufficient to expressly open the claim to mixtures of the recited alternatives. In this case, the absence of such language in the ’055 patent claims created a presumption to the contrary.

Based on the intrinsic record, however, the court found this presumption to be overcome. Here, alternatives A, B, C, and D were chemically related and to some extent overlapping. Additionally, the specification disclosed various blends of the resins. Finally, dependent claim 24 specified “wherein at least one layer comprises a blend of at least two of said resins.” Based on this intrinsic record, the court reversed the district court’s construction regarding blends and vacated the grant of summary judgment of non-infringement.

Judge Taranto dissented, disagreeing with the construction adopted by the majority in excluding unlisted resins from the independent claims. The dissent found the claim language to be unclear with respect to the relationship between the term “layer” and the four classes of resins listed in the group, noting that the language in the independent claims departs from the typical Markush format of a genus defined by species within a group. The dissent viewed the term “layer” as implying a structure, characterized by a spatial relationship and possibly by its shape, and found imprecise the recitation of a spatially or shape-defined “layer” being limited by materials from which it could be made. Due to what Judge Taranto perceived as a semantic uncertainty, he disagreed that the claims should be construed to exclude unlisted resins.

The Multilayer decision emphasizes the need for careful use and consideration of Markush claims, most significantly as follows:

  • A Markush claim to a structure “selected from the group consisting of alternatives A, B, and C” will be strongly presumed to permit only those alternatives. This presumption is not likely to be rebutted even if the specification describes other alternatives, and even if there is a dependent claim that specifies other alternatives.
  • A Markush claim to a structure “selected from the group consisting of alternatives A, B, and C” will be presumed not to permit mixtures of A+B, A+C, etc. This presumption might be rebutted if the specification describes mixtures or if there are dependent claims that specify mixtures.
  • A Markush claim to a structure “selected from the group consisting of alternatives A, B, and C and mixtures thereof” is likely to be held to expressly encompass mixtures of such alternatives.
  • As evidenced by the split in the Federal Circuit panel, there are no absolutes. Each patent is construed in accordance with its intrinsic record, and even experienced judges can disagree about how a Markush claim should be construed.

For more information on this decision, please contact Fitch Even attorneys Allen E. Hoover or Giles N. Turner, the authors of this alert.


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