United States: Implicit Redefinition Of Claim Scope

Although "the words of a claim are generally given their ordinary and customary meaning," Thorner v. Sony Computer Entm't Am. LLC, 669 F.3d 1362, 1365-67 (Fed. Cir. 2012), if the specification reveals "a special definition given to a claim term by the patentee that differs from the meaning it would otherwise possess[,] . . . the inventor's lexicography governs," Phillips v. AWH Corp., 415 F.3d 1303, 1316 (Fed. Cir. 2005) (en banc).  The Federal Circuit has recognized that determining when a patentee is acting as his own lexicographer can be difficult because "the distinction between using the specification to interpret the meaning of a claim and importing limitations from the specification into the claim can be a difficult one to apply in practice."  Id. at 1323; see also Bell Atl. Network Servs., Inc. v. Covad Commc'ns Grp., Inc., 262 F.3d 1258, 1268 (Fed. Cir. 2001).  Recently, in SkinMedica, Inc. v. Histogen, Inc., No. 2012-1560 (Fed. Cir. Aug. 23, 2013), the Federal Circuit revisited many of its claim-construction principles, taking a close look at how to determine when a patentee has chosen to be his own lexicographer. 

At issue in SkinMedica were U.S. Patent Nos. 6,372,494 ("the '494 patent") and 7,118,746 ("the '746 patent"), owned by SkinMedica.   The '494 and '746 patents contain claims related to methods for producing pharmaceutical compositions containing "novel conditioned cell culture medium compositions" and uses for those compositions.  SkinMedica appealed the district court's construction of the claim term "culturing . . . cells in three-dimensions."  The specifications of the '494 and '746 patents refer at several points to methods of culturing cells in two dimensions, using microcarrier beads, and in three dimensions.  SkinMedica argued that the ordinary meaning of "culturing cells in three dimensions" includes growing cells using beads, which was the method allegedly used by the accused infringer Histogen, and that the district court should have interpreted the claim term according to this ordinary meaning.  The district court, however, held that, based on statements made in the specification and during the prosecution history, the patentee acted as his own lexicographer and narrowed the scope of "culturing . . . cells in three-dimensions" by excluding the use of beads. 

In order to determine whether a patentee has, in fact, chosen to be his own lexicographer and use terms in a manner other than according to their ordinary meaning, the court must examine the available intrinsic evidence.  See Bell Atl., 262 F.3d at 1268.  A court need not find an explicit redefinition of a claim term in order to hold that the ordinary meaning of the term does not apply.  Id.  Instead, a claim term may be clearly redefined by implication such that the meaning may be "found in or ascertained by a reading of the patent documents."  Id. (citing Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582, 1584 n.6 (Fed. Cir. 1996)).  The Court noted in Vitronics, for example, that when a patentee uses a claim term throughout the entire patent specification in a manner consistent with only a single meaning, he has defined that term "by implication."  Id.  After a thorough analysis, that is precisely what the Court in SkinMedica concluded the patentees did through the consistent differentiation of beads from cells grown in three dimensions.

First, the Court analyzed the patentee's use of disjunctives, such as "or" and "as opposed to," to differentiate cells grown in three dimensions from cells grown on beads in several instances in the specification and prosecution history.  The Court analyzed the following passages in the specification:

  • "Cell lines grown as a monolayer or on beads, as opposed to cells grown in three-dimensions, lack the cell-cell and cell-matrix interactions characteristic of whole tissue in vivo." 
  • "The cells are cultured in a monolayer, beads (i.e., two dimensions) or, preferably, in three-dimensions."
  • "The cells may be cultured in any manner known in the art including in monolayer, beads or in three-dimensions . . . ."

The Court found that the use of the disjunctive phrase "as opposed to" makes it clear that the patentee considered cells grown on beads to be different and distinct from cells grown in what is considered to be three dimensions.  Similarly, relying on precedent, the Court found that the word "or" plainly designates that a series describes alternatives, and that SkinMedica's use of the word "or" distinguishes beads from cells grown in three dimensions.  See Kustom Signals, Inc. v. Applied Concepts, Inc., 264 F.3d 1326 (Fed. Cir. 2001).  Thus, the Court found that because these distinctions are consistent with the remainder of the specification, they constitute an implicit redefinition of the terminology.

Second, the Court analyzed language in the specification and prosecution history distinguishing beads from cells grown in three dimensions, such as:

  • "Conventional conditioned cell culture medium, medium cultured by cell-lines grown as a monolayer or on beads, is usually discarded or occasionally used in culture manipulations such as reducing cell densities."
  • "Culturing cells in three-dimensions results in the production of a conditioned medium having a different chemical composition than that of cells cultured by conventional means."

The Court relied upon prior precedent as it reasoned that emphasizing a particular attribute of the invention can operate as a disclaimer of claim scope.  See, e.g., SafeTCare Mfg. Inc. v. Tele-Made, Inc., 497 F.3d 1262, 1269-70 (Fed. Cir. 2007).  In SafeTCare, the Federal Circuit found that, because the specification repeatedly emphasized its invention as applying pushing forces, not pulling forces, the inventor made it clear that this attribute of the invention is important in distinguishing the invention over the prior art and, in effect, disclaims the use of pulling forces.  Similarly, in Edwards Lifesciences LLC v. Cook Inc., 582 F.3d 1322, 1333 (Fed. Cir. 2009), the Court emphasized that "[w]here the general summary or description of the invention describes a feature of the invention . . . and criticizes other products . . . that lack that same feature, this operates as a clear disavowal of these other products . . ."  (citing Astrazeneca AB v. Mut. Pharm. Co., 384 F.3d 1333, 1340 (Fed. Cir. 2004)).

Applying these principles in SkinMedica, the Court found that statements in the specification and prosecution history repeatedly distinguished the three-dimensional cultures from cell-lines grown using beads to demonstrate the novelty of the medium produced by three-dimensional cultures.  Consistent with prior case law, the Court found that this emphasis on a particular mode of operation, especially to avoid prior art, operated as a disclaimer of the otherwise broad scope of the claim term at issue.  See SafeTCare, 497 F.3d at 1270.  The Court relied on SkinMedica's consistent emphasis of this distinction between beads and three dimensions throughout the specification and prosecution history to find that the distinction was, in effect, a redefinition by implication of the claim term "culturing . . . cells in three dimensions."  See Bell Atl., 262 F.3d at 1271-73.

Lastly, the Court analyzed SkinMedica's use of "i.e." throughout the specification.  The Court found that the inventors use of the phrase "i.e." throughout the specification, about twelve times in total, to introduce an explanation or definition of a word or phrase, demonstrated the inventors' intent to define "beads" when they wrote "beads (i.e., two dimensions)."  This is consistent with the Court's prior holding in Edwards Lifesciences, in which the Federal Circuit held that a patentee's use of "i.e." in the specification "signals an intent to define the word to which it refers."  582 F.3d at 1334.¹

The SkinMedica case serves as yet another reminder that statements made both in the specification and during prosecution must be carefully considered so as not to later limit claim scope.  Special attention should be paid to the use of words such as "or" and "as opposed to" when drafting specifications to ensure that they are only used when a distinction is required.  The Federal Circuit has also reemphasized that "i.e." is typically used to define a term, regardless of where in the specification it is used.  Practitioners should use this term sparingly, and consciously, in patent applications, making sure to use it only when intended to provide a definition.  Being aware of these potential pitfalls will assist in avoiding unintentional disclaimer of claim scope.


1. Despite SkinMedica's various arguments that the Court's definition was inconsistent with references cited on the face of the patents or within the patents, and with its expert's testimony, the Court declined to give much weight to this extrinsic evidence in light of the consistent and repetitive redefinition of the claim term through the intrinsic evidence, including the prosecution history and the specification.

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