'Containing' and 'Mixture' Are Open-Ended Terms That Do Not Exclude Unlisted Elements
In a recent case, the U.S. Court of Appeals for the Federal Circuit ruled that the claim terms "containing" and "mixture," like the term "comprising," are open-ended, transitional terms that do not exclude the presence of additional, unrecited elements.
Mars Inc. owns a patent (6,312,746) on an animal food product. Mars sued Heinz for patent infringement. The key claim in the case recited a pet food product having a soft inner component "containing a mixture of lipid and solid ingredients." The district court held that the limitation was close-ended and must include only lipid and solid ingredients. It based its construction on statements in the specification indicating that the soft inner component should "not exceed 100 wt%" of lipids and solids and that "the most preferred embodiment comprises about '60 wt% solids and 40 wt% lipids.'" Further, the district court found that, while other claim limitations used the term "containing at least," Claim 1 did not, thus indicating Mars' intent for the inner component to be exclusive of ingredients other than lipids and solids. Based upon the claim construction, the district court granted Heinz’s motion for summary judgment of noninfringement.
On appeal, Mars first argued that the district court erred in holding that the term "ingredients" in the phrase "a mixture of solid and lipid ingredients" refers only to starting materials. The Federal Circuit agreed that the claims were not so limited. It first pointed to a dictionary definition for "ingredient" as "something that enters into a compound or is a component part of any combination or mixture." Noting that a second dictionary definition for "ingredient" is very similar, the court concluded that the ordinary meaning of "ingredients" can refer to either the starting materials (e.g., as in a recipe) or to the components of a mixture after they have been combined. The Court also noted that the first dictionary defines "mixture" as "a product of mixing," or more specifically "a combination of several different kinds of some article of consumption." The Court reasoned that since the claims here are for "a mixture ... of ingredients," this wording strongly suggests that "ingredients" refers to the components after they have been combined to form that "mixture." Accordingly, the court concluded that the ordinary meaning of "a mixture of lipid and solid ingredients" refers to the components of the inner component at any time after they have been mixed together.
Next, the court concluded that neither "containing" nor "mixture" in the disputed phrase requires that the ingredients be limited to those ingredients listed in the claim itself. In other words, like the term 'comprising,' the terms 'containing' and 'mixture' are open-ended. On this point, the Court noted that the dictionary definition and the Manual of Patent Examining Procedure use "containing" synonymously with "comprising" and "including" and that the MPEP treats these transitional terms as open-ended and "not exclud[ing] additional, unrecited elements or steps." Accordingly, the Court found that neither the dictionary nor the MPEP provides a definition for "containing" that excludes additional, unnamed ingredients.
The Federal Circuit then found that the district court erred in concluding that the specification was inconsistent with the ordinary, open-ended meaning of the terms "containing" and "mixture." According to the Court, the passage in the specification that mentions "preferable" amounts of lipids and solids does not, as the district court concluded, bar a sum weight percentage of solids and lipids less than 100 percent. Also, the mere fact that the minimum and maximum values of the stated ranges equal 100 percent does not suggest that the sum percentages of solids and lipids must always equal 100 percent. Rather, the Court reasoned that "the specification recites a range of values in which the weight percentage of lipids and solids may vary given the presence of additional, unnamed ingredients."
Finally, the Court found that the district court erroneously relied on the absence of the phrase "at least" in construing "containing a mixture of lipid and solid ingredients" as excluding ingredients other than lipids and solids from the inner shell. The Court explained that when Mars used "at least" in the context of the outer shell limitation, it did so to make clear that not all, but "at least" one, of the listed ingredients must be present. Thus, the use of "at least" to describe the outer shell did not even suggest that "containing" is close-ended.
For more information, please contact the author, Patrick G. Gattari of McDonnell Boehnen Hulbert & Berghoff LLP, at (312) 935-2375 or at firstname.lastname@example.org.
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