When does Describing an Embodiment become a Clear and Unmistakable Disclaimer?

By Laura Witbeck

What rises to the level of being a disclaimer of claim scope?  In other words, when do expressions made in the intrinsic evidence of a patent rise to the level of clearly disclaiming the scope of the claims from just providing background and explanation of concepts in the patent?  As of now, wording and context of patents at issue are analyzed in a case-by-case basis using general guidelines set out by long standing case law.

Case law typically requires claims be given their ordinary and customary meaning, as a person of ordinary skill in the art in question would understand the claim terms at the time they were written.[1]  Both intrinsic evidence (i.e., the patent itself, including the claims, specification and, if in evidence, prosecution history of the patent) and relevant extrinsic evidence may be used to identify how such person of ordinary skill in the art would interpret the meaning of the claims.[2]  As most relevant to claim construction, the claim terms themselves are first considered.[3]  However, a patentee may define a term differently from its ordinary meaning by clearly setting forth the definition of the claim term in the patent specification and/or file history.[4]  Thus, the specification has been held to be highly relevant to determining whether a claim term has been used inconsistently with its ordinary meaning, and is considered by the Federal Circuit to be “the single best guide to the meaning of a disputed term.”[5]  If in evidence, the prosecution history of a patent is also relevant (although less so than the specification) in determining meaning of claim terms, as it provides evidence of how the patent office and the inventor understood the patent.[6]  For example, a patentee may express limitations as to how the meaning of certain terms or concepts should be understood in the specification and/or the prosecution history of a patent.  The Federal Circuit has held that if the claims are to be limited by disclaimers made in the specification or prosecution history, there must be “a clear and unmistakable disclaimer.”[7]

A new precedential case from the Federal Circuit, Continental Circuits v. Intel Corp., __ F.3d __ (Fed. Cir. Feb. 8, 2019), provides an example of “the difficulty in drawing the ‘fine line between construing the claims in light of the specification and improperly importing a limitation from the specification into the claims.’”[8]  In Continental Circuits, the claims at issue (from multiple related patents) relate to multilayer electrical devices that use teeth formed on a layer’s surface to mechanically grip a second layer.  Formation of the teeth is described in the patent specifications and prosecution history as using a double desmear process that has advantages over single pass desmear processes of the prior art.

In Continental Circuits, the Federal Circuit reviewed the claim construction by 1) looking at the plain language of the claims; 2) reading the claims in view of the specification; and 3) using the prosecution history to support claim construction.  Because none of the reviewed claims actually recite a “repeated desmear process,” the court found that the plain language of the claims did not support construction limited to a repeated desmear process.  Analysis of claim construction based on the specification and prosecution history was much more in depth due to the extensive discussion of using a double desmear process to form the claimed surface geometry in the specification and prosecution history.

In the specification, the patentee explains that “[o]ne technique for forming the teeth” is the double desmear process, which is “contrary to all known teachings in the prior art.”[9]  The patents at issue further use terms of optionality, such as “can” and “for example,” to describe ways the invention “can be carried out.”  The Federal Circuit concluded that the phrases used in the patents at issue, such as “one technique,” “can be carried out,” and “a way,” are used to describe how to make the claimed invention using one method that is different from the prior art process. However, such terms do not lead to a finding of clear disavowal of claim scope without more evidence.  This part of the analysis falls under established case law guidelines that when a patent describes only a single embodiment, the claims will not necessarily be construed as being limited to that embodiment.[10]

Similarly, in the prosecution history, an expert declaration responding to indefiniteness and written description rejections pointed out passages in the written description reciting “a technique which forms the teeth” by “performing two separate swell and etch steps.”  The court found that such statements merely explain one technique for forming teeth and do not clearly and unmistakably disavow claim scope.

The Federal Circuit also found that use of phrases such as “contrary to” and “in stark contrast” were used in the context of describing advantages of a preferred embodiment over prior art methods.  In other words, the court found that the disclosed double desmear process was merely being compared and contrasted to prior art techniques, which does not rise to the level of a clear disavowal of claim scope.  This part of the analysis falls under established case law guidelines that “[m]ere criticism of a particular embodiment … is not sufficient to rise to the level of clear disavowal.”[11]

Established case law also recognizes that descriptions of “the present invention” as a whole may be used to limit the scope of the invention to such description.[12]  Examples of when this guideline is not dispositive include when the references to the “invention” are not uniform, or when “other portions of the intrinsic evidence do not support applying the limitation to the entire patent.”[13]  Continental Circuits provides an example of these exceptions, and thus further clarifies when describing what “the present invention” is limits or does not limit the scope of the invention.  In applying these exceptions to the scenario in Continental Circuits, the court first cited statements in the specification that “the present invention can be carried out by a new use…” and “the present invention differs from the common desmear process in that sub-steps in the desmear process are repeated as a way of forming the teeth.”[14]  The court explained that such statements were intrinsic evidence that did not support applying the limitation of forming teeth with the double desmear process to the entire patent because they disclose only one way to carry out the present invention rather than characterizing the present invention “as a whole.”  Secondly, the court explained that the use of “the present invention” throughout the patents did not uniformly require use of the limitation of forming teeth with the double desmear process.  For example, the court noted that use of the double desmear process was not mentioned in the summary of the invention section at all, which made it difficult to say that the present invention “as a whole” requires such limitation.

In the conclusion of Continental Circuits, the Federal Circuit found that the lower court erred in reading a “repeated desmear process” limitation into the claims.  From the court’s analysis, we can draw a few practice tips for making sure limitations are not read into the claims post-issue. First, patent applicants should avoid statements that uniformly describe and/or refer to “the invention” as including unnecessary limitations. Secondly, patent applicants should also use terms of optionality when describing embodiments of the invention, such as, “for example,” “can,” “not limited to,” “a way,” etc.

[1] See, e.g., Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005).

[2] Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996).

[3] Id.

[4] See, e.g., Vitronics, 90 F.3d at 1582; Thorner v. Sony Comput. Entm’t Am. LLC, 669 F.3d 1362, 1365 (Fed. Cir. 2012); and CCS Fitness, Inc. v. Brunswick Corp., 288 F.3d 1359, 1366 (Fed. Cir. 2002).

[5] Vitronics, 90 F.3d at 1582.

[6] See, e.g., Phillips, 415 F.3d at 1317; and Markman v. Westview Instruments, Inc., 52 F.3d 967, 980 (Fed. Cir. 1995).

[7] See, e.g., Thorner, 669 F.3d at 1367; and Retractable Techs., Inc. v. Becton, Dickinson & Co., 653 F.3d 1296, 1306 (Fed. Cir. 2011) (“To disavow claim scope, the specification must contain ‘expressions of manifest exclusion or restriction, representing a clear disavowal of claim scope.’” (quoting Epistar Corp. v. Int’l Trade Comm’n, 566 F.3d 1321, 1335 (Fed. Cir. 2009)).

[8] Retractable Techs., 653 F.3d at 1305.

[9] U.S. Patent No. 7,501,582, col. 5, ll. 40-44 (emphasis added).

[10] See, e.g., Phillips, 415 F.3d at 1323; and Liebel-Flarsheim Co. v. Medrad, Inc., 358 F.3d 898, 906 (Fed. Cir. 2004) (“Even when the specification describes only a single embodiment, the claims of the patent will not be read restrictively unless the patentee has demonstrated a clear intention to limit the claim scope using ‘words or expressions of manifest exclusion or restriction.’” (quoting Teleflex, Inc. v. Ficosa N. Am. Corp., 299 F.3d 1313, 1327 (Fed. Cir. 2002))).

[11] Thorner, 669 F.3d at 1366.

[12] Verizon Servs. Corp. v. Vonage Holdings Corp., 503 F.3d 1295, 1308 (Fed. Cir. 2007).

[13] Absolute Software, Inc. v. Stealth Signal, Inc., 659 F.3d 1121, 1136-37 (Fed. Cir. 2011).

[14] ‘582 Patent, col. 6, ll. 41-48 and col. 8, ll. 49-52.