'977 claims a method for cooling a person via evaporation by using a multi-layered liquid-retaining composite with a fiberfill batting material. In the first round, Technique Solutions, the defendant, dodged literal infringement because its garments use a combination of natural and synthetic fiberfill. While the district court had found no doctrine of equivalents infringement because of prosecution estoppel, the CAFC found that the prosecution history was not so damning. 

The district court construed the claim language to require only synthetic batting material and found no literal infringement because Vizorb® includes natural fibers. The district court also found that the claim of infringement under the doctrine of equivalents was barred by prosecution history estoppel.

On appeal we affirmed the district court’s finding of no literal infringement. We concluded that, though the prosecution history was ambiguous, the examples of fiberfill in the specifications, the three patents incorporated by reference, and the extrinsic evidence (dictionaries and other industry sources) all suggested that fiberfill was synthetic material. AquaTex, 419 F.3d at 1381. However, we held that prosecution history estoppel did not bar consideration of infringement by equivalents because “[t]he argument [made during prosecution]…does not address or even relate to the composition of the fiberfill batting” and “[t]he subject matter surrendered by the narrowing amendment bears no relation to the composition of the fiberfill batting material.” AquaTex, 419 F.3d at 1383. We remanded to the district court to “consider whether or not each limitation of the claims in dispute, or its equivalent, is present in the accused Techniche products.” Id.

On remand, the district court found again prosecution estoppel, and, alternatively, the that claimed filler was for a different function than the accused product filler; thus, insufficient equivalence.

The district court granted summary judgment of non-infringement. It held that AquaTex’s narrowing amendments made during prosecution of the ’977 patent “surrender[ed] subject matter within which [Techniche’s] product falls” and therefore AquaTex was barred by prosecution history estoppel from asserting infringement by equivalents. AquaTex Indus., Inc. v. Techniche Solutions, No. 3:02-0914, 2006 WL 1006631, at *8 (M.D. Tenn. Apr. 13, 2006). Alternatively, the district court held that AquaTex had failed to prove that Techniche’s “filler layer performs substantially the same function in substantially the same way as” AquaTex’s patented method because it had not shown that Techniche’s “filler layer includes a hydrophobic material, like the fiberfill used in [AquaTex’s] product, to create air pockets to promote evaporation.” Id. at *6, 7-8.

Aquatex appealed, hoping for infringement through doctrine of equivalents. Functionality is the key issue here.

Reliance on the doctrine of equivalents may be foreclosed by prosecution history estoppel. Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 30 (1997). Under this doctrine, the surrender of subject matter during patent prosecution creates a presumption that the patentee is precluded from recapturing that subject matter through the doctrine of equivalents; this presumption can be rebutted by the patentee through a showing that an amendment was unrelated to patentability. See id. at 30-33; see also Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 733-34, 740 (2002).

A finding of infringement under the doctrine of equivalents requires a showing that the difference between the claimed invention and the accused product or method was insubstantial or that the accused product or method performs the substantially same function in substantially the same way with substantially the same result as each claim limitation of the patented product or method. AquaTex, 419 F.3d at 1382; see also Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 608 (1950) (“[A] patentee may invoke this doctrine [of equivalents] to proceed against the producer of a device ‘if it performs substantially the same function in substantially the same way to obtain the same result.’” (quoting Sanitary Refrigerator Co. v. Winters, 280 U.S. 30, 42 (1929))). We have held that the function, way, result inquiry focuses on “an examination of the claim and the explanation of it found in the written description of the patent.” Vehicular Techs. Corp. v. Titan Wheel Int’l, Inc., 141 F.3d 1084, 1090 (Fed. Cir. 1998); see also Warner-Jenkinson, 520 U.S. at 40 (“An analysis of the role played by each element in the context of the specific patent claim will thus inform the inquiry as to whether a substitute element matches the function, way, and result of the claimed element.”).

Interestingly, the claimed fiberfill was ascribed a negative function, something the district court overlooked, and with which the CAFC found error.

In addition to finding the doctrine of equivalents barred by prosecution history estoppel, the district court concluded that Vizorb® was not equivalent to the “fiberfill batting material” limitation because AquaTex failed to show that “Defendant’s filler layer includes a hydrophobic material, like the fiberfill used in Plaintiff’s product, to create air pockets to promote evaporation.” AquaTex, 2006 WL 1006631, at *6 (emphasis added). It appears that the district court concluded that the function of the “fiberfill batting material” was to promote evaporation and that Vizorb® did not achieve this function in the same way (i.e., by the use of hydrophobic material and by the creation of air pockets) as this limitation. Neither Techniche nor the district court made any effort to relate these alleged differences to the distinction between natural and synthetic fibers.

There is nothing in the “fiberfill batting limitation” of claims 1 and 9 of the ’977 patent, nor in the specification, that indicates that its function is to promote evaporation. The “fiberfill batting material” claim itself does not indicate any specific function beyond general service as part of the filler layer. The only function given to the fiberfill in the specification is a negative function: “any commercial fiberfill may be used as long as it does not adversely affect the performance of the end composite.” ’977 patent col. 3 ll. 48-50 (emphasis added). Thus, promotion of evaporation is not a function of the fiberfill identified in the claims or the specification of the ’977 patent; instead the specification only says that the fiberfill cannot retard evaporation (i.e., the performance of the end composite).

The district court used evidence from the patentee's web site, describing its product, as confirmation of its interpretation. The CAFC ruled this completely inappropriate. Only intrinsic evidence counts.

This reliance on the characteristics of the patentee’s product was erroneous. “Infringement, either literally or under the doctrine of equivalents, does not arise by comparing the accused product…with a commercialized embodiment of the patentee.” Johnson & Johnston Assocs. Inc. v. R.E. Serv. Co., 285 F.3d 1046, 1052 (Fed. Cir. 2002) (en banc) (internal quotation marks omitted); see also Donald S. Chisum, 5A Chisum on Patents § 18.04[1][b] (2005). Similarly, we noted in Amstar Corp. v. Envirotech Corp., 730 F.2d 1476 (Fed. Cir. 1984), “[i]nfringement is not determined…by comparison between commercial products sold by the parties.” Id. at 1481-82. As discussed above, the identification of the elements of the function, way, result test solely “entails an examination of the claim and the explanation of it found in the written description of the patent,” as well as “[i]n some cases[] the patent’s prosecution history.” Vehicular Techs., 141 F.3d at 1090. This inquiry leaves no room for consideration of the patentee’s product.

So, Aquatex was set up for a win. All it had to do was meet its burden of proving infringement under the doctrine of equivalents. This required "provide particularized testimony and linking argument on a limitation-by-limitation basis that created a genuine issue of material fact as to equivalents" "from the perspective of someone skilled in the art."

AquaTex, as the plaintiff, was required to prove (by a preponderance of the evidence) infringement under the doctrine of equivalents. PSC Computer Prods., Inc. v. Foxconn Int’l, Inc., 355 F.3d 1353, 1357 (Fed. Cir. 2004); CVI/Beta Ventures, Inc. v. Tura LP, 112 F.3d 1146, 1161 (Fed. Cir. 1997). In Texas Instruments, Inc. v. Cypress Semiconductor Corp., 90 F.3d 1558 (Fed. Cir. 1996), we set forth the patentee’s evidentiary burden under the doctrine of equivalents:

Pursuant to our precedent, a patentee must…provide particularized testimony and linking argument as to the ‘insubstantiality of the differences’ between the claimed invention and the accused device or process, or with respect to the function, way, result test when such evidence is presented to support a finding of infringement under the doctrine of equivalents. Such evidence must be presented on a limitation-by-limitation basis. Generalized testimony as to the overall similarity between the claims and the accused infringer’s product or process will not suffice.

Id. at 1567 (emphasis added). “The same rule applies in the summary judgment context.” Network Commerce, Inc. v. Microsoft Corp., 422 F.3d 1353, 1363 (Fed. Cir. 2005). Thus, AquaTex was required to provide particularized testimony and linking argument on a limitation-by-limitation basis that created a genuine issue of material fact as to equivalents. See id. In particular AquaTex was required to provide particularized testimony and linking argument to show the equivalents of a synthetic filler layer and Techniche’s product’s filler layer, which was partially composed of natural fibers.

Both the Supreme Court and this court have made clear that the evidence of equivalents must be from the perspective of someone skilled in the art, for example “through testimony of experts or others versed in the technology; by documents, including texts and treatises; and, of course, by the disclosures of the prior art.” See Graver Tank & Mfg. Co., 339 U.S. at 609; see also Texas Instruments, 90 F.3d at 1566. But, while many different forms of evidence may be pertinent, when the patent holder relies on the doctrine of equivalents, as opposed to literal infringement, the difficulties and complexities of the doctrine require that evidence be presented to the jury or other fact-finder through the particularized testimony of a person of ordinary skill in the art, typically a qualified expert, who (on a limitation-by-limitation basis) describes the claim limitations and establishes that those skilled in the art would recognize the equivalents.

Stupidly, Aquatex offered only fluff, a deposition from its CEO, not the detailed testimony required; its entire enforcement effort wasted by legal sloth.

It did not specifically address equivalents or compare Techniche’s product to the patented method on a limitation-by-limitation basis as required by Texas Instruments. See also Warner-Jenkinson, 520 U.S. at 29 (“[T]he doctrine of equivalents must be applied to individual elements of the claim, not the invention as a whole.”). Nor does it satisfy the Texas Instruments requirement of testimony on the “insubstantiality of the differences between the claimed invention and the accused device or process” or “the function, way, result test.” 90 F.3d at 1567 (internal quotation marks omitted); see also Lear Siegler v. Sealy Mattress Co. of Mich., 873 F.2d 1422, 1426 (Fed. Cir. 1989) (“It is clear that LSI did not elicit testimony explicitly comparing the claimed and accused devices as to all three elements of equivalence.”).

So -

The district court erred in finding the doctrine of equivalents barred by prosecution history estoppel and in comparing the accused product to the patentee’s commercial embodiment. However, AquaTex failed to show the existence of a genuine issue of material fact or provide any particularized testimony on equivalents. Summary judgment was therefore appropriate.