Equivalent can be "foreseeable" and thus barred under Festo even when equivalence unknown in the art
July 05, 2007

Today, the Federal Circuit rendered the latest decision in the nearly 20 year saga of Festo. The court refined the rules set forth by the Supreme Court in its Festo decision, specifically when an equivalent is unforeseeable, and thus not barred by prosecution history estoppel. The majority of the panel held that:

an alternative is foreseeable if it is disclosed in the pertinent prior art in the field of the invention. In other words, an alternative is foreseeable if it is known in the field of the invention as reflected in the claim scope before amendment.

Notably, however, it is not necessary that the "known" equivalent be known to be equivalent. As a result, because the alleged equivalent in this case was known in the prior art, it was foreseeable, even though it was not known that it was technically equivalent, that is, it met the legal test for equivalents.

Judge Newman dissented, arguing that:

this court has confounded the issue by creating a new and incorrect criterion for the measurement of "foreseeability," the court now holding that an existing structure need not be recognized, or even recognizable, as an equivalent at the time of the patent application or amendment, in order to be "foreseeable" if it is later used as an equivalent.

Could Festo be heard en banc by the Federal Circuit a third time? One commentator already thinks so.

The patent at issue relates to magnetic rodless cylinders. These cylinders have diverse uses, from sewing equipment to the Big Thunder Mountain Railroad ride at Walt Disney World. The claimed cylinders have a "sleeve" surrounding them. During prosecution, the claims at issue were amended to require that the sleeve be "magnetizable." The accused product does not use a magnetizable sleeve, but instead uses an aluminum sleeve that provides the same result.

Festo originally brought suit in 1988. The case has been up and down the federal court system over the last 19 years, so a short summary of the various decisions is helpful for reference:

  1. District court judgment of infringement under the doctrine of equivalents after jury trial (1994)
  2. Federal Circuit panel affirms the judgment (1995)
  3. Supreme Court vacates and remands for reconsideration in light of Warner-Jenkinson Co. v. Hilton Davis Chem. Co. (1997)
  4. On remand, a Federal Circuit panel vacates and remands the district court's judgment (1999)
  5. Federal Circuit grants petition for rehearing en banc (1999)
  6. Federal Circuit, en banc, reverses, holding that amendments related to patentability are an absolute bar to the doctrine of equivalents (2000)
  7. The Supreme Court grants certiorari (2001)
  8. The Supreme Court vacates and remands, finding that prosecution history estoppel is not a complete bar to the doctrine of equivalents, and setting forth conditions where prosecution history estoppel does not apply, including when an equivalent is unforeseeable (2002)
  9. Federal Circuit requests briefing on various issues relevant to the remand from the Supreme Court (2002)
  10. The Federal Circuit, en banc again, provides further guidance for application of the Supreme Court's holding, including that equivalents are more likely to be unforeseeable if they "represent[] 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," and remands the case for a determination on the issue of foreseeability (2003)
  11. The district court holds that the alleged equivalent was foreseeable, and thus prosecution history estoppel applies, and there can be no infringement under the doctrine of equivalents (2005)
  12. The district court enters an additional order affirming its previous decision and denying a motion to amend the judgment (2006)
  13. Today's decision.

The district court made two important findings for purposes of the decision. First, the court found that that aluminum sleeves such as those used by the accused device were known in the prior art. Second, the court found it was undisputed "that the use of an aluminum alloy sleeve for purposes of shielding magnetic fields was not known at the time of amendment." Based on these findings, the district court found use of an aluminum sleeve foreseeable because of the "very small" magnetic leakage from the cylinders.

The majority of the Federal Circuit panel affirmed. Most notably, the panel majority held that if the alleged equivalent is known in the prior art, it is foreseeable for Festo purposes even if it was unknown in the art that the alleged equivalent was, in fact, equivalent. As applied to this case, this meant that because aluminum sleeves were known in the art, they were foreseeable notwithstanding the fact that it was unknown in the art that they would work as an equivalent. As stated by the court:

an alternative is foreseeable if it is disclosed in the pertinent prior art in the field of the invention. In other words, an alternative is foreseeable if it is known in the field of the invention as reflected in the claim scope before amendment.

. . .

We conclude that use of an aluminum alloy sleeve was foreseeable at the time of amendment because the pertinent prior art disclosed a non-magnetizable sleeve. Festo could have claimed use of a non-magnetizable sleeve but did not do so. Accordingly, we find that the equivalent was surrendered by amendment.

Judge Newman takes the majority to task for "stray[ing] from controlling precedent as well as from logic." In her view, what matters is whether it was known that the alleged equivalent was, in fact, equivalent at the time of the amendment. She states:

The panel majority is incorrect in ruling that "the foreseeability requirement does not require the knowledge that the equivalent would satisfy the function/way/result test or the insubstantial differences test." Maj. op. at 18. How can a particular equivalent be foreseeable, if it was not known that the technology was equivalent in the context of the invention?

She further characterizes the rule crafted by the majority as a "complete bar [to the doctrine of equivalents] by another name," a phrase used by the Supreme Court in its 2002 Festo decision.

Given the history of the Festo case and the importance for guidance on the scope of the Festo rule regarding unforeseeable equivalents, it seems that this case may be considered by the Federal Circuit en banc for a third time.

Tidbits: MVS attorney Kurt Van Thomme wrote a law review article regarding the Festo line of cases in 2005. Also, MVS attorney Kirk Hartung wrote an article regarding application of the doctrine of equivalents, including Festo implications, published in the August 2004 issue of the Journal of the Patent and Trademark Office Society.

To read the full decision in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., click here.

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