“Consisting of:” Not as Narrow as You Think

• Aug 25 2016
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• Category: News

By: William Valet

The transitional phrases “comprising” and “consisting of” are well defined terms of art in Patent Law; the former being inclusive and the latter being exclusive.[1]  For example, a claim reciting “ ‘a safety razor blade unit comprising a guard, a cap, and a group of first, second, and third blades’ encompasses razors with more than three blades because the transitional phrase ‘comprising’ in the preamble and the phrase ‘group of’ are presumptively open-ended.”[2]  In contrast, a claim reciting “ ‘consisting of’ excludes any element, step, or ingredient not specified in the claim.”[3]

Conventional wisdom would seem to indicate then, that the use of the phrase “consisting of” would not merit further evaluation.  However, as evidenced in Multilayer Stretch Cling Film Holdings, Inc. v. Berry Plastics Corporation (“Multilayer”), “consisting of” still raises issues that bewilder practitioners and the court alike, particularly in the context of Markush claim language.  Such is the uncertainty, that Multilayer produced a dissent and a denied petition for sanctions by Berry Plastics Corporation (“Berry”) against Multilayer Stretch Cling Film Holding, Inc. (“Multilayer”) for “ ‘bas[ing] its entire pre-suit investigation on a frivolous claim construction that flies in the face of well-settled patent law.’ ”[4]  What then, is the effect of the phrase “consisting of” on claim breadth when used in the context of Markush claim language?  The answer, according to the court in Multilayer, is it depends.

The court in Multilayer was tasked with interpreting independent claims 1 and 28 of Multilayer’s U.S. Patent No. 6,265,055 (“the ’055 patent”).  For purposes of brevity, only claim 1 will be discussed, which recites,

1. A multi-layer, thermoplastic stretch wrap film containing seven separately identifiable polymeric layers, comprising:

(a)         two identifiable outer layers, at least one of which having a cling performance of at least 100 grams/inch, said outer layer being selected form the group consisting of linear low density polyethylene, very low density polyethylene, and ultra low density polyethylene resins, said resins being homopolymers, copolymers, or terpolymers, of ethylene and alpha-olefins; and

(b)        five identifiable inner layers, with each layer being selected from the group consisting of linear low density polyethylene, very low density polyethylene, ultra low density polyethylene, and metallocene-catalyzed linear low density polyethylene resins; said resins are homopolymers, copolymers, or terpolymers, of ethylene and C₃ to C₂₀ alpha-olefins;

wherein each of said two outer layers and each of said five inner layers have different compositional properties when compared to a neighboring layer.[5]

The court in Multilayer focused their analysis on element (b) of independent claim 1, which the parties stipulated was written in Markush claim format.[6]  Therefore, the issues upon appeal in Multilayer are twofold: “first, whether the Markush group of element (b) is closed to resins other than the listed four, and, second, whether the Markush group is closed to blends of the four listed resins.”[7]

In analyzing the first issue, the court rejected Multilayer’s argument that the inner layers of element (b) were open to other resins than those listed in the Markush group, stating that

[t]o construe the inner layers of element (b) as open not only to the four recited resins but also to any other polyolefin resin conceivably suitable for use in a stretchable plastic cling film would be to construe the claims to cover any plastic film with five compositionally different inner layers, each of which contains any amount of one of the four recited resins.  Construing element (b) in this manner would render the ’055 patent’s Markush language – “each layer being selected from the group consisting of” – equivalent to the phrase “each layer comprising one or more of.”[8]

The court qualified this statement by noting that although the phrase “consisting of” “creates a very strong presumption that the claim element is ‘closed’ and therefore ‘exclude[s] any elements, steps, or ingredients not specified in the claim’ ”[9] and “is at least a century old and has been reaffirmed many times by our court and other courts,”[10] a patentee may “overcome the exceptionally strong presumption that a claim term set off with ‘consisting of’ is closed to unrecited elements . . . [if] the specification and prosecution history . . . unmistakably manifest an alternative meaning.”[11]  Therefore, the use of the phrase “consisting of” is not terminal to the breadth of the claim.

In an attempt to satisfy this burden and broaden the scope of the claim, Multilayer pointed to several instances in the specification of the ’055 patent where unrecited resins, notably low density polyethylene (LDPE), are mentioned as a suitable for use in both inner and outer layers.[12]  This argument was summarily rejected by the court, which stated that mere “listing of these other resins in the specification is [not] sufficient to overcome the [strong] presumption created by the ‘consisting of’ claim language.”[13]

Multilayer further argued that the remaining claims of the ’055 patent are indicative that element (b) is not limited to those resins recited in the Markush group.  Specifically, Multilayer proffered that “[b]ecause claim 10 includes the additional limitation of low density polyethylene in one of said five inner layers, it necessarily follows that claim 1 already permits the use of low density polyethylene in the inner layers.’ ”[14]  Such a principle, according to Multilayer, is supported by Ortho-McNeil, which states that a court should “strive[] to reach a claim construction that does not render claim language in dependent claims meaningless.”[15]

While the court acknowledged that “ ‘it is true that dependent claims can aid in interpreting the scope of claims from which they depend,’ ”[16] the argument must ultimately fail because “ ‘they are only an aid to interpretation and are not conclusive.’ ”[17]  Indeed, “the language of a dependent claim cannot change the scope of an independent claim whose meaning is clear on its face,”[18] for “ ‘[t]he dependent claim tail cannot wag the independent claim dog.’ ”[19]  The court ultimately determined that “the specification of the ’055 patent, including its dependent claims, is insufficient to overcome the very strong presumption . . . that the Markush group of element (b) is closed to resins other than the four recited.”[20]

An unintended result of Multilayer’s argument is that the claim construction announced by the court necessitated that claim 10 be found invalid.  Much to the chagrin of Multilayer, the court stated “[a] dependent claim that contradicts, rather than narrows, the claim from which it depends is invalid.” [21]  Since the court found that “[i]ndependent claim 1 excludes LDPE from the inner layers, while dependent claim 10 includes it . . . claim 10 is inconsistent with claim 1 and, indeed, contradicts claim 1,”[22] claim 10 (along with claims 18 and 19) must be found to be invalid.

The court then shifted its focus to the question of “whether element (b) of claims 1 and 28 is closed to blends of LLDPE, VLDPE, ULDPE, and mLLDPE.”[23]  The court makes an important distinction between the first issue of whether element (b) was closed to resins other than those listed in the Markush group, and the second issue of whether element (b) is closed to blends of the resins listed in the Markush group.  This distinction is a small but important one, for “[b]y itself, the use of the transitional phrase ‘consisting of’ does not necessarily suggest that a Markush group is closed to mixtures, combinations, or blends.”[24]  Thus, “a layer could still ‘consist’ of the listed resins even if the layer ‘consists’ of a mixture of those resins.”[25]  The court qualified this notion by stating that “[n]onetheless, we held in Abbott that there is a presumption that a Markush group is closed to mixtures of the listed elements.”[26]  Typically, to open a Markush group to mixtures, the patentee would need to add specific language, such as “and mixtures thereof,” and “at least one member of the group.”[27]  Guided only by this standard, “the Markush group of element (b) is . . . closed to blends.”[28]  However, the Abbott standard is not absolute.  The court stated that the presumption that element (b) is closed to blends can be overcome “by a combination of other claim language and the specification itself.”[29]  However, this “presumption that Markush claims are closed to blends is distinct from, and not as strong as, the presumption that unlisted resins are excluded.”[30]

Here, the court initially looked to the claims of the ’055 patent, and noted that “it is clear on its face that the term ‘linear low density polyethylene’ (LLDPE) [as recited in claim 1] is one that encompasses at least metallocene-catalyzed linear low density polyethylene (mLLDPE), as mLLDPE is, by its very terms, a subtype of LLDPE prepared with a particular kind of catalyst.”[31]  The court concluded that “[i]t follows that claim[] 1 . . . contemplate[s] the use of polyolefin resins that are classifiable both as an LLDPE and as an mLLDPE, which supports reading element (b) as open to ‘blending’ LLDPE and mLLDPE within a single layer (and open to other blends of the listed resins).”[32]

Moreover, the specification of the ’055 patent provided further evidence that element (b) is open to blends of the resins recited in the Markush group, with the court noting, amongst other instances, “[a]ccording to the patent’s Abstract, ‘[t]he resins used in the film composition . . . may be blended to achieve a desired range of physical or mechanical properties of the final film product.”[33]  The court found that this intrinsic evidence was strong enough to overcome the presumption that the element (b) is closed to blends, and therefore, “the Markush group of element (b) must be read as open to blends of the four listed resins.”[34]  In view of the above analysis and conclusion that claims 1 and 28 are open to blends of LLDPE, VLDPE, ULDPE, and mLLDPE, the court vacated the district court’s grant of summary judgment and remanded for further consideration.

Finally, the court dismissed Berry’s cross-appeal alleging the district court had abused its discretion in denying their motion for sanctions; the court stating that“[t]his case presents numerous close and difficult questions of claim construction, as shown by the fact that we disagree (in part) with the district court’s interpretation of the inner layers of the claimed film . . . [and therefore] the district court did not abuse its discretion in declining to impose sanctions under Rule 11.”[35]

Multilayer illustrates that claim construction revolving around the transitional phrase “consisting of” is a complicated and thorough endeavor.  While it is well settled that “consisting of” “excludes any element, step, or ingredient not specified in the claim,”[36] it is clear that there is a general misconception that “consisting of” is per se closed to elements not listed in the claim, rather than a presumption.

But what lessons can practitioners glean from Multilayer?  The initial reaction is to avoid the use of “consisting of” and Markush language altogether.  In the majority of instances this would be a wise approach.  However, in certain instances the use of such claim language still has value, particularly in the chemical context or in dependent claim format to avoid excess claim fees.  Additionally, MPEP § 2111.03 states that “[w]hen the phrase ‘consists of’ appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.”[37]  In this manner, if used with precision, “consisting of” or Markush language can be a useful tool to prevent a claim from reading on prior art. 

 While it may seem prudent to add as much evidence in the specification as possible that the group is not to be limited to those elements listed in the claim, Multilayer does not clearly define how much evidence is required to overcome the presumption that the claim is closed to any element, step, or ingredient not specified in the claim.  Therefore, practitioners should utilize “consisting of” only in those instances where the forthcoming elements are to be construed as being limited solely to those elements listed after “consisting of.”  Further, practitioners should try to limit the use of Markush language to dependent claims to obtain the broadest interpretation of independent claims and to ensure that dependent claims are not rendered invalid for being inconsistent with the independent claim. 

 If nothing else, Multilayer reminds practitioners that they should be mindful of how they draft claims.  If “consisting of” or Markush language must be used, practitioners should be comfortable with the claim being limited to those elements listed after “consisting of” and should pay particular attention to whether or not they intend to claim blends or mixtures of the recited elements, in which case “and mixtures thereof” or other similar language should be utilized.