In Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co. (Fed. Cir. September 26, 2003) (“Festo IX”), the Federal Circuit on remand from the Supreme Court considered whether Festo could rebut the presumption that the filing of narrowing amendments for the patents in suit surrendered all subject matter between the original claim limitations and the amended claim limitations.

BACKGROUND

            Festo filed suit in 1988 against Shoketsu Kinzoku Kogyo Kabushiki Co. and SMC Pneumatics, Inc. (collectively “SMC”) for infringement of U.S. Patent No. 4,354,125 to Stoll and U.S. Patent No. B1 3,779,401 to Carroll relating to magnetically coupled rodless cylinders (“Festo I”).  The claims of the Stoll and Carroll patents failed to literally cover SMC’s device, and a dispute centered on possible coverage under the doctrine of equivalents.

• Original claim 1 of the Stoll patent recited a linear motor having a piston, a driven assembly, and a magnet arrangement and was amended during prosecution to require that the driven member include a cylindrical sleeve made of a magnetizable material.  In contrast, SMC’s accused device has a sleeve made of a nonmagnetizable material, aluminum.
• The claims of both the Stoll and Carroll patents were amended during prosecution to include “sealing ring” limitations.  In contrast, SMC’s accused device includes a single, two-way sealing ring.
  • Original claim 1 of the Stoll patent recited that the linear motor includes a piston with “sealing means at each end” and was amended to recite “first sealing rings” and “second sealing rings.”
  • Original claim 1 of the Carroll patent did not mention any sealing rings and was amended (as new claim 9 during reexamination) to recite “a pair of resilient sealing rings.”

The district court granted partial summary judgment that SMC’s accused device infringed the Carroll patent claim under the doctrine of equivalents, and a jury found that SMC’s accused device infringed the Stoll patent claim under the doctrine of equivalents. 

On appeal, the Federal Circuit (“Festo VI”) heard the case en banc and held no range of equivalents was available for the amended claim limitations under the following complete bar approach to the doctrine of equivalents when prosecution history estoppel arises:

• a “substantial reason related to patentability” that may give rise to an estoppel is not limited to overcoming prior art under 35 U.S.C. § 102 or § 103, but encompasses other reasons relating to the statutory requirements for a patent, including compliance with 35 U.S.C. § 112;
• a “voluntary” claim amendment — i.e., one neither required by a patent examiner nor made in response to a rejection by an examiner for a stated reason — may give rise to prosecution history estoppel;
• no range of equivalents is available for an amended claim limitation when prosecution history estoppel applies; and
• “unexplained” amendments are not entitled to any range of equivalents.

 The Federal Circuit determined that the Stoll and Carroll patent claims had been narrowed by amendments and Festo had failed to establish reasons for those amendments unrelated to patentability.  So, no range of equivalents was available and SMC was not liable for patent infringement. 

            On appeal, the Supreme Court (“Festo VIII”) disagreed with the Federal Circuit’s complete bar approach and instead established a presumption that a narrowing amendment made for a reason of patentability surrenders the entire territory between the original claim limitation and the amended claim limitation.  A patentee may overcome that presumption by showing that “at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent” because:

1)      the equivalent would have been unforeseeable at the time of the amendment;

2)      the rationale underlying the amendment bore no more than a tangential relation to the equivalent in question; or

3)      there was some other reason suggesting that the patentee could not reasonably be expected to have described the insubstantial substitute in question.

The Supreme Court observed that the narrowing amendments in the Stoll and Carroll patents were made for reasons of patentability, and remanded for either the Federal Circuit or the district court to determine whether Festo can demonstrate that those narrowing amendments did not surrender the particular equivalents in question.

MAJORITY OPINION

            On remand, the Federal Circuit summarized the operation of the presumptions outlined by the Supreme Court in Festo VIII and Warner-Jenkinson (Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997)) as follows.

• The first question in a prosecution history estoppel inquiry is whether an amendment filed in the Patent and Trademark Office has narrowed the literal scope of a claim.  If the amendment was not narrowing, then prosecution history estoppel does not apply.
• But if the accused infringer establishes that the amendment was narrowing, then the second question is whether the reason for that amendment was a substantial one relating to patentability.  When the prosecution history record reveals no reason for the narrowing amendment, Warner-Jenkinson presumes that the patentee had a substantial reason relating to patentability.  Consequently, the patentee must show that the reason for the amendment was not one relating to patentability if it is to rebut that presumption.  A patentee’s rebuttal of the Warner-Jenkinson presumption is restricted to the evidence in the prosecution history record.  If the patentee successfully establishes that the amendment was not for a reason of patentability, then prosecution history estoppel does not apply.
• If, however, the court determines that a narrowing amendment was made for a substantial reason relating to patentability — whether based on a reason reflected in the prosecution history record or on the patentee’s failure to overcome the Warner-Jenkinson presumption — then the third question in a prosecution history estoppel analysis addresses the scope of the subject matter surrendered by the narrowing amendment.  At that point Festo VIII imposes the presumption that the patentee has surrendered all territory between the original claim limitation and the amended claim limitation.  The patentee may rebut that presumption of total surrender by demonstrating that it did not surrender the particular equivalent in question according to the three criteria identified in Festo VIII (listed above and discussed below).  Finally, if the patentee fails to rebut the Festo presumption, then prosecution history estoppel bars the patentee from relying on the doctrine of equivalents for the accused element.  If the patentee successfully rebuts the presumption, then prosecution history estoppel does not apply and the question whether the accused element is in fact equivalent to the limitation at issue is reached on the merits.

The Federal Circuit also stated that the rebuttal of the presumption of surrender is a question of law to be determined by the court, not a jury, and provided general guidance on the relevant factors encompassed by each of the three criteria for rebuttal of the presumption of surrender.

1)      The first criterion requires a patentee to show that an alleged equivalent would have been “unforeseeable at the time of the amendment and thus beyond a fair interpretation of what was surrendered.”  This criterion presents an objective inquiry, asking whether the alleged equivalent would have been unforeseeable to one of ordinary skill in the art at the time of the amendment.

·        Usually, if the alleged equivalent represents later-developed technology (e.g., transistors in relation to vacuum tubes, or Velcro® in relation to fasteners) or technology that was not known in the relevant art, then it would not have been foreseeable.

·        In contrast, old technology, while not always foreseeable, would more likely have been foreseeable.  Indeed, if the alleged equivalent were known in the prior art in the field of the invention, it certainly should have been foreseeable at the time of the amendment.

2)      The second criterion requires a patentee to demonstrate that “the rationale underlying the narrowing amendment [bore] no more than a tangential relation to the equivalent in question.”  In other words, this criterion asks whether the reason for the narrowing amendment was peripheral, tangential, or not directly relevant to the alleged equivalent.

·        For example, an amendment made to avoid prior art that contains the equivalent in question is not tangential:  it is central to allowance of the claim.

3)      The third criterion requires a patentee to establish “some other reason suggesting that the patentee could not reasonably be expected to have described the insubstantial substitute in question.”

·        The third criterion may be satisfied when there was some reason, such as the shortcomings of language, why the patentee was prevented from describing the alleged equivalent when it narrowed the claim.

 RULINGS

The Federal Circuit viewed the relation between the Stoll and Carroll patent claims and the accused device’s aluminum sleeve and sealing ring elements as follows.

• By amending the Stoll patent claim during prosecution to add the limitation that the driven member includes “a cylindrical sleeve made of a magnetizable material,” the patentee presumptively disclaimed the entire territory between the original limitation and the amended limitation, i.e., any driven member that does not have “a cylindrical sleeve made of a magnetizable material.”  SMC’s accused device includes a sleeve made of aluminum, a nonmagnetizable material.  Thus, the question is whether Festo can show that the “magnetizable” amendment did not surrender an aluminum sleeve.
• The Stoll patent claim originally recited “sealing means at each end” and was amended during prosecution to recite “first sealing rings” and “second sealing rings,” so the patentee presumptively surrendered all “sealing means” other than two-ring structures.  The Carroll patent claim was amended during reexamination to require “a pair of resilient sealing rings,” so the patentee presumptively disclaimed devices that include other than two sealing rings.  SMC’s accused device includes a single, two-way sealing ring.  Thus, the question is whether Festo can demonstrate that the two “sealing ring” amendments did not surrender a single two-way sealing ring.

With respect to the “magnetizable” and “sealing ring” amendments, the Federal Circuit ruled Festo satisfied neither the “tangentiality” criterion nor the “some other reason” criterion, but remanded the case to the district court for a determination whether Festo could satisfy the “unforeseeability” criterion.  With respect to the “magnetizable” amendment, the court stated:

1)      Although it seems unlikely that an aluminum sleeve would have been unforeseeable, as it was made of a commonly available metal, Festo argues that one skilled in the art at the time of the “magnetizable” amendment would not have foreseen the interchangeability of an aluminum alloy sleeve and a magnetizable alloy sleeve in Stoll’s small gap design involving rare earth magnets.  Factual issues thus exist as to whether an ordinarily skilled artisan would have thought an aluminum sleeve to be an unforeseeable equivalent of a magnetizable sleeve in the context of the invention.

2)      Because the Stoll prosecution history reveals no reason for the “magnetizable” amendment and because Festo still identifies no such reason, Festo has not shown that the rationale for the “magnetizable” amendment was only tangential to the accused equivalent.

3)      There was no linguistic or “other” limitation to prevent Stoll from describing the accused equivalent.  Although Stoll chose to claim a “magnetizable” sleeve, he reasonably could have been expected to have described a sleeve made of a common nonmagnetizable material, such as aluminum, if that were what he intended to claim.  For example, Stoll could have described the accused equivalent at various levels of specificity by using a common descriptive term such as “aluminum” or “metal.”

With respect to the “sealing ring” amendments, the court stated:

1)      Festo argues that SMC’s two-way sealing ring was an inferior and unforeseeable equivalent of the one-way sealing rings located at each end of the piston in the claimed invention.  Factual issues thus exist as to whether a person of ordinary skill in the art would have considered the accused two-way sealing ring to be an unforeseeable equivalent of the recited pair of sealing rings.  The case is therefore remanded to the district court to determine, with the presentation of evidence as the district court sees fit, the objective unforeseeability of a single two-way sealing ring.

2)      The “sealing ring” amendments were made to distinguish prior art patents based, at least in part, on the “sealing ring” aspect of the invention.  Therefore, Festo cannot establish that the rationales underlying the “sealing ring” amendments were only tangentially related to SMC’s accused sealing ring.

3)      It cannot be said that there was a linguistic or “other” limitation preventing description of the equivalent in question when the difference between the claimed limitation and the accused equivalent is principally a difference in quantity.  Instead of reciting “first sealing means . . . and second sealing means” or “a pair of . . . sealing rings,” the patentees easily could have encompassed SMC’s sealing ring by claiming, for example, “at least one sealing ring.”

OPINION CONCURRING IN PART AND DISSENTING IN PART

The opinion of Judges Newman and Mayer discusses various matters that may impact the further proceedings of this case and other doctrine of equivalents cases, as follows.

• The majority opinion hypothesizes that Festo could have presented a claim to “at least one sealing ring,” and thus rules that the surrendered territory includes the accused SMC single sealing ring, although no such claim was requested.  Festo points out that if such a claim had been presented for reexamination it would have been subject to rejection as new matter or for enlarged claim scope prohibited by 35 U.S.C. §305.
• The Stoll patent was filed as a translation of a counterpart German patent application and original claim 1 recited “sealing means” for the internal surface, original claim 4 (dependent from “claims 1 to 3”) recited “sealing rings,” and claim 13 added during prosecution recited “first sealing rings” and “second sealing rings.”  Festo argues that the original claims, construed in light of the specification, do not include the SMC single two-way sealing ring.  Festo also argues that since “sealing rings” were claimed in original claim 4, the territory surrendered between the original and amended claims of the Stoll patent does not include the single two-way sealing ring.  Although claim 1 was broader than claim 4, both were original claims.  The issue of the role of dependent or subordinate claims in determining the surrendered territory needs resolution.  It is improper simply to assume that all potential equivalents are surrendered in all cases, whatever the nature and scope of the original claims and whatever the relation of the amendment to the original claims.
• It is incongruous that equivalency in fact follows from foreseeable interchangeability (Warner-Jenkinson), yet the patentee must now prove unforeseeability in order to gain access to the doctrine of equivalents.
• The majority opinion limits the evidence of the “tangentiality” criterion to the prosecution record.  However, the factors relevant to a determination of tangential relation are unlikely to reside in the prosecution record, for unrelated subject matter or unknown equivalents are unlikely to have been discussed by either the examiner or the patentee.  The issue of “tangentiality” may require consideration of how the reason for an amendment affected the patentee’s view that certain technology was extraneous.  The prosecution record rarely discusses devices that are not prior art.
• To satisfy the “some other reason” criterion, the majority rules Festo must show that some reason prevented Stoll from describing the accused aluminum equivalent.  The court imposes the requirement that the patentee actually was prevented from describing an unknown equivalent, in order to rebut the presumption of surrender — and that the reason was contained in the prosecution history — a virtual impossibility.

October 10, 2003

Text Copyright © 2003 Bob Brill et al.

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