Opinion ID: 771385
Heading Depth: 2
Heading Rank: 2

Heading: Warner-Jenkinson

Text: 22 In this en banc rehearing, we focus our attention on the effect of Warner-Jenkinson on our case law relating to the doctrine of equivalents and prosecution history estoppel. Festo V, 187 F.3d at 1381-82, 51 USPQ2d at 1959-60; see alsoShoketsu Kinzoku Kogyo Kabushiki Co. v. Festo Corp., 520 U.S. 1111 (1997) (Festo III) (remanding the case for further consideration in light of the Warner-Jenkinson decision). 23 The patent before the Court in Warner-Jenkinson disclosed an improved process for purifying dyes which used a method called ultrafiltration. Warner-Jenkinson, 520 U.S. at 21. During prosecution, the patentee amended the claims to recite that the process is carried out at a pH from approximately 6.0 to 9.0. Id. at 22. The accused process was carried out at a pH of 5.0. Id. at 23. In light of these facts, the Supreme Court embarked on an endeavor to clarify the proper scope of the doctrine of equivalents. Id. at 21. 24 The Court dismissed the arguments of Warner-Jenkinson (the alleged infringer) that the doctrine of equivalents, as established in Graver Tank, did not survive the 1952 revision of the Patent Act. Id. at 25-27. The Court nevertheless noted its concern that the doctrine of equivalents, as it has come to be applied since Graver Tank, has taken on a life of its own. Id. at 28-29. The Court agreed with Warner-Jenkinson that Graver Tank did not dispose of prosecution history estoppel as a legal limitation on the doctrine of equivalents. Id. at 30. However, the Court rejected Warner-Jenkinson's argument that the reason for an amendment during patent prosecution is irrelevant to any subsequent estoppel. Id. The Court noted that [i]n each of our cases cited by petitioner and by the dissent below, prosecution history estoppel was tied to amendments made to avoid the prior art, or otherwise to address a specific concern--such as obviousness--that arguably would have rendered the claimed subject matter unpatentable. Id. at 30-31. The Court therefore saw no substantial cause for requiring a more rigid rule invoking an estoppel regardless of the reasons for a change. Id. at 32 (footnote omitted). 25 Turning to the facts at hand, the Court noted that, although the parties did not dispute that the upper pH limit of 9.0 was added to avoid the prior art, the reason for adding the lower limit of 6.0 is unclear. Id. Presented with the problem . . . where the record seems not to reveal the reason for including the lower pH limit of 6.0, the Court place[d] the burden on the patent holder to establish the reason for an amendment required during patent prosecution. Id. at 33. The Court stated that courts will have to decide whether the [proffered] reason is sufficient to overcome prosecution history estoppel as a bar to application of the doctrine of equivalents to the element added by that amendment. Id. The Court also stated that [w]here no explanation is established, . . . the court should presume that the patent applicant had a substantial reason related to patentability for including the limiting element added by the amendment. Id. Therefore, prosecution history estoppel would bar the application of the doctrine of equivalents as to that element. Id. Because Hilton Davis had not proffered in . . . [the Supreme] Court a reason for the addition of the lower pH limit, the Court remanded the case for this court to consider whether Hilton Davis had offered reasons for the amendment that added the lower pH limit and to determine whether Hilton Davis should be given the opportunity to establish such reasons. Id. at 34. 26 The Court rejected the other restrictions on the doctrine of equivalents proposed by Warner-Jenkinson. Id. at 35-40. Specifically, the Court refused to require judicial exploration of the equities of a case before allowing application of the doctrine of equivalents, id. at 34, refused to require proof of intent on the part of the alleged infringer before the doctrine of equivalents could be applied, id. at 35-36, and refused to adopt independent experimentation as an equitable defense to the doctrine of equivalents, id. at 36. The Court also refused to limit the doctrine of equivalents to equivalents that are disclosed within the patent itself, reasoning that the proper time for evaluating equivalency . . . is at the time of infringement, not at the time the patent was issued. Id. at 37. 27 In closing, the Court stated that it chose to adhere to the doctrine of equivalents, which should be applied as an objective inquiry on an element-by-element basis. Id. at 40. The Court noted that [p]rosecution history estoppel continues to be available as a defense to infringement. Id. However, if the patent holder demonstrates that an amendment required during prosecution had a purpose unrelated to patentability, a court must consider that purpose in order to decide whether an estoppel is precluded. Id. at 40-41. If the patent holder is unable to establish such a purpose, a court should presume that the purpose behind the required amendment is such that prosecution history estoppel would apply. Id. at 41.