Argument-Based Estoppel From Ambiguous Prosecution History Did Not Bar Application of the Doctrine of Equivalents

Case: Aquatex Indus. v. Techniche Solutions (Fed. Cir. 8/19/05 - No. 05-1088)

The One Sentence Summary: In a dispute about whether "fiberfill" filling for evaporative cooling garments could include natural fibers, the district court erred in holding that argument-based prosecution history estoppel barred application of the doctrine of equivalents.

What They Were Fighting About: Aquatex owns the '977 patent for a method of using an evaporative cooling garment with a water absorbing "fiberfill" filler that is soaked in water and then cools the wearer as the water evaporates. The district court granted summary judgment of noninfringement to Techniche, holding that the term "fiberfill" did not include natural fibers, and that the doctrine of equivalents could not be applied due to prosecution history estoppel.

Federal Circuit Holdings:

• The claim was for contributory rather than direct infringement because the '977 patent was not for the material itself. "Because the ’977 patent claims the use of evaporative cooling garments, rather than the actual multi-layer fabric itself, AquaTex’s cause of action is one for contributory infringement under 35 U.S.C. § 271(c). Although not directly infringing, a party may still liable for inducement or contributory infringement of a method claim if it sells infringing devices to customers who use them in a way that directly infringes the method claim.** R.F. Del., Inc. v. Pac. Keystone Techs., Inc., 326 F.3d 1255, 1267 (Fed. Cir. 2003). "Liability for either active inducement of infringement or for contributory infringement is dependent upon the existence of direct infringement." Joy Techs., Inc. Flakt, Inc., 6 F.3d 770, 774 (Fed. Cir. 1993)."
• The specification supported the limitation of the term "fiberfill" to synthetic fibers because the specification cited three prior patents as reference for fiberfill, all of which referred to synthetic fibers. Slip Opinion at 9.
• The prosecution history was ambiguous as to the meaning of the term "fiberfill" because the applicant did not respond directly to the examiner's argument that a mix of natural and synthetic fibers was a fiberfill.
• The definitions and usage of the term "fiberfill" in dictionaries and industry publications was consistent with a definition limiting it to synthetic fibers such as polyester.
• The district court properly found no literal infringement.
• The doctrine of equivalents should have been considered by a jury. "However, "[t]he doctrine of equivalents allows the patentee to claim those insubstantial alterations that were not captured in drafting the original patent claim but which could be created through trivial changes." Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 733 (2002) ("Festo II"). Infringement under the doctrine of equivalents requires that the accused product contain each limitation of the claim or its equivalent. Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 40 (1997). An element in the accused product is equivalent to a claim limitation if the differences between the two are insubstantial. The analysis focuses on whether the element in the accused device "performs substantially the same function in substantially the same way to obtain the same result" as the claim limitation. Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 608 (1950) (internal quotation omitted). "
• Argument-based prosecution history estoppel did not apply here. "Prosecution history estoppel can prevent a patentee from relying on the doctrine of equivalents when the patentee relinquishes subject matter during the prosecution of the patent, either by amendment or argument. Pharmacia & Upjohn Co. v. Mylan Pharm., Inc., 170 F.3d 1373, 1376-77 (Fed. Cir. 1999). "The doctrine of prosecution history estoppel limits the doctrine of equivalents when an applicant makes a narrowing amendment for purposes of patentability, or clearly and unmistakably surrenders subject matter by arguments made to an examiner." Salazar, 2005 U.S. App. LEXIS 13517, at *6; see Festo II, 535 U.S. at 736 (narrowing amendment for purposes of patentability); Eagle Comtronics, Inc. v. Arrow Communication Labs., Inc., 305 F.3d 1303, 1316 (Fed. Cir. 2002) (argument-based estoppel). [¶] While at least one claim limitation was added here to overcome an anticipation rejection during the prosecution of the patent, Techniche does not allege amendment-based estoppel. Instead it asserts argument-based estoppel. To invoke argument-based estoppel, the prosecution history “must evince a clear and unmistakable surrender of subject matter.” Pharmacia, 170 F.3d at 1377 (internal quotation omitted). To determine if subject matter has been relinquished, an objective test is applied, inquiring “whether a competitor would reasonably believe that the applicant had surrendered the relevant subject matter.” Cybor Corp., 138 F.3d at 1457."