The Federal Circuit issued a new opinion applying the analysis in Festo II in an effort to offer guidance to lower courts in applying the flexible (versus absolute) bar approach to the doctrine of equivalents. The new interpretation and application of amended patent claims seem to put additional burden on patent prosecutors.
In Festo III , Festo Corporation sued Shoketsu Kinzoku Kogyo Kabushiki Co. (“SMC”) for patent infringements of the Stoll and Carroll Patents (U.S. Patent No. 4,354,125 and 3,779, 401, respectively). After the PTO examiner rejected the original Stoll claims for indefiniteness, two new limitations were added during the prosecution – one dealing with the containment of a pair of sealing rings and another specifying that the cylindrical sleeve is made of magnetizable material. Carroll added the same requirement of a pair of sealing rings during a reexamination proceeding to further specify the invention and distinguish it from prior art references. SMC made a similar device, employing a single sealing ring with a two-way lip instead of Festo’s one-way sealing ring. Both patents claimed magnetically coupled rodless cylinders. The trial court ruled for Festo, applying the doctrine of equivalents. Under the doctrine, even if not all of the claimed elements are found literally in the accused device, a patent may nonetheless be extended to cover the accused device if there are insubstantial differences from the patent claims.
On appeal, the Federal Circuit reversed the lower court’s decision implementing a complete bar approach to the doctrine of equivalents, reasoning that since the claim had been narrowed during its prosecution, there was no range of equivalents available under the doctrine.
The Supreme Court rejected the complete bar approach and established a rebuttable presumption that an amendment made by the patentee that narrows the scope of the claim relinquishes the claimed element or equivalent. If the patentee cannot rebut the presumption, (s)he is restricted to the literal scope of the amended claim. The presumption can be overcome by establishing that the accused equivalent was either: 1) unforeseeable at the time of the amendment; (2) that the rationale underlying the amendment had no more than a tangential relation to the equivalent in question; or 3) for some difficulty in claiming the equivalent.
If the court looks at whether the alleged equivalent would have been “foreseeable to one of ordinary skill in the art at the time of the amendment” in order to rebut the presumption that an amendment is related to patentability, it may consider any evidence, expert testimony in particular, commenting on the foreseeability of the equivalent. This would seem to implicate that older technology is more likely to be foreseeable and hence, precluded.
The tangentially-related inquiry requires a court to look at the prosecution history of a patent. Expert testimony may still be utilized in interpreting the prosecution history since no additional evidence to prove the narrowing amendment was not directly related to the alleged equivalent is allowed.
The third prong in overcoming the presumption seems to be open to interpretation as to what kind of evidence is admissible in demonstrating why an alleged equivalent was not described at the time of the claim amendment.
One of the implications of the Court’s decision is that a patent prosecutor must avoid rejections that require narrowing amendments. A claim amendment may cause an equivalent to be lost. Facing such consequences, patent prosecutors have to be diligent in framing the literal language of the claim. As a result, a prosecutor might want to utilize the PTO examiner interviews more widely in order to progress towards admission of the patent.
A practical approach in avoiding amendments might call for framing narrow claims in the original application that would likely not be subjected to a rejection requiring a narrowing amendment. Another option is that the prosecutor may choose to file multiple applications directed to a common subject matter in order to avoid prosecution history estoppel or even a number of independent claims ranging in scope that might result in the PTO examiner allowing the more narrowly framed ones (resulting in non-amended claims.) A different strategy might involve filing claims that cover different grounds related to the patent, such as methods of production, product claim, etc. that might increase the odds of having a claim that is not amended. Naturally, the clarity and structure of the claims are of utmost importance since clarifying amendments must also be avoided.
If a narrowing amendment has to be made, the prosecutor needs to ensure that the maximum reach of the literal scope of the claims is reached. Hence, the prosecutor might consider a wider use of approximation terms. Alternatively, the prosecutor might rewrite and file a new claim (Festo has not dealt with this situation explicitly and hence, its application is unclear.)
Of course, there is always the option of appeal when a rejection of a claim is based on material deficiencies or prior art. However, the process is very time consuming and would increase the cost of prosecution.
Overall, the Festo III decision will require additional effort on the part of the patent prosecutor which will translate into increased costs of the patenting process. The indirectly raised patent filing standards might potentially result in better quality work product that might further impact the patenting system by decreasing the number of claims bouncing between the PTO and patent prosecutors.
Sources:
1. Fu, Alan, The Unfinished Tasks of Festo: What More Needs to Be Done to Balance the Doctrine of Equivalents and Prosecution History Estoppel, at http://www.law.berkeley.edu/institutes/bclt/pubs/annrev/exmplrs/drft/festodrft.pdf
2. Kaminski, M., The Post-Festo World of Equivalents, at http://www.jmls.edu/ripl/vol2/issue2/kaminski.pdf
3. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 234 F.3d 558 (2000)
4. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 122 S.Ct. 1831 (2002)
