The much anticipated Festo case decision by the U.S. Supreme Court is a decidedly mixed bag, depending on which side of a particular patent your interests may lie.
The U.S. Supreme Court reversed the absolute bar rule propounded by the Federal Circuit in the Festo case. In its unanimous decision (Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. ____, 2002 Lexis 3818 (May 28, 2002), the court emphasized that the issue of equivalents, like the related issue of estoppel that was the focus of its 1997 decision in Warner-Jenkinson, is not amenable to a bright-line rule. The Supreme Court accepted the U.S. Court of Appeals for the Federal Circuit proposition that any amendment that narrows the scope of a claim for any reason related to patentability may give rise to a prosecution history estoppel. But the court did not accept the more controversial aspect of the Federal Circuit decision that an estoppel absolutely bars the application of the doctrine of equivalents (DOE) with respect to the narrowed claim element. Rather, the Supreme Court created a presumption that equivalence would be barred and placed the burden of proving that the estoppel does not preclude coverage of the particular equivalent in issue on the patentee. The patentee may overcome the 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 to literally encompass the alleged equivalent.
The Federal Circuit
The doctrine of equivalents is an equitable doctrine, which the courts have developed over several years to prevent others from using the substance of an invention by making only an insubstantial change. In turn, the courts developed the doctrine of prosecution history estoppel to limit the application of the doctrine of equivalents in order to prevent the recapture of subject matter surrendered to distinguish the patent claims over prior art.
The subject matter involved in the Festo case relates to a magnetically coupled rodless cylinder, as might be used in a conveyor application. The claimed device comprises a fluid-driven piston that moves back and forth within the cylinder. A sleeve mounted on the outside of the cylinder moves back and forth with the movement of the piston, due to magnetic coupling between magnets on the piston and magnets within the outer sleeve. In addition to the magnets, the claimed invention recited that the piston has a pair of guide rings, which provide a sliding fit for the piston within the cylinder. During prosecution, the applicant amended the independent claim to recite "plural guide rings … and first sealing rings located axially outside said guide rings." The amended version of the claim also specified that the sleeve was made of a magnetizable material.
The accused SMC devices only used one sealing ring instead of two and did not have magnetizable sleeves. Hence, the district court found no literal infringement. However, the district court found on summary judgment that the accused devices infringed one of the patents in suit under the doctrine of equivalents, and the jury had found that the accused devices infringed another patent under the doctrine of equivalents. Hence, at the time of the en banc decision by the Federal Circuit, the SMC devices had been found to be only insubstantially different from the claimed subject matter.
In its en banc decision, Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 234 F.3d 558 (Fed. Cir. 2000), the Federal Circuit held that any required or voluntary amendment that narrows the scope of a claim for any reason related to the statutory requirements for a patent will give rise to prosecution history estoppel with respect to the amended claim element. The Federal Circuit also imposed a new, bright-line rule to apply in the event of such an estoppel: Any time a patentee narrows a claim element for a reason related to patentability, there would be no range of equivalents available for the amended claim element. Under this absolute bar, the degree of difference between the alleged equivalent and the element in the claim is irrelevant, no matter how insubstantial.
In applying its new rule, the Federal Circuit found that the claim amendments created an estoppel and held that as a matter of law, Festo could not assert the SMC devices were equivalent to the amended claim elements because the estoppels simply barred application of the doctrine of equivalents absolutely.
The Supreme Court
The Supreme Court accepted the Federal Circuit holding that any narrowing amendment made for a reason related to patentability gives rise to an estoppel. Thus, the law is now clear that an estoppel may arise based on an amendment made to comply with §112, just as with an amendment made to define an invention over prior art.
However, as to the scope of the resulting estoppel, the Supreme Court found the imposition of the absolute bar to be overreaching by the Federal Circuit and vacated that portion of the decision. Instead, the Supreme Court imposed new rebuttable presumption against equivalence. Although not an absolute bar, in most cases, this presumption will likely lead to the same result as the absolute bar rule. However, it is likely to require more litigation to get there.
The modified "flexible" bar adopted by the Supreme Court was the approach advocated by the U.S. Justice Department (representing the U.S. Patent and Trademark Office) as amicus curiae. Specifically, the Supreme Court held that the patentee, as the author of the amended claim language, bears the burden of establishing that the surrender attendant the narrowing amendment does not encompass the particular equivalent in question. The rationale for this burden is that the patentee may be expected to give careful consideration to various ways to redefine its claim and, in so doing, should reasonably be expected to draft amended claims encompassing readily known equivalents.
The result is a rebuttable presumption, which the patentee must overcome, that the scope of the estoppel created by the narrowing amendment surrenders any subject falling in scope between the original claim language and the amended claim language. Some possibilities suggested by the court to rebut the presumption would be for the patentee to establish that the equivalent in question was "unforeseeable at the time of the application" or 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. The patentee may also attempt to rebut the presumption by establishing that the rational underlying the amendment bears "no more than a tangential relation to the equivalent in questions."
Any amendment that narrows a claim for any reason relating to patentability may create an estoppel barring equivalents with regard to the narrowed claim element. Although the resulting bar is not necessarily absolute, there is now a presumption that the patentee disclaimed any subject matter falling between the original claim scope and the narrowed claim scope, which typically will include the alleged equivalent. The burden is on the patentee to overcome this presumption by showing that a skilled artisan drafting the claim would not reasonably have been expected to have written the claim to literally encompass the allegedly equivalent. Thus, although the patentee now has an opportunity to rebut the presumption, the need to prove a negative expectation in connection with the possibility of drafting a claim that would literally cover the alleged equivalent is likely to create a host of new issues in future patent litigation.
Narrowing Amendments ~ It should be expected that every claim amendment made during prosecution will be closely scrutinized in litigation to determine if it was narrowing. The key evidence relevant to this inquiry is likely to be what the patent prosecutor does and says in the record before the U.S. Patent and Trademark Office. Litigation is likely to focus on two issues: when is an amendment narrowing and what is a reason relating to patentability. To some extent the Federal Circuit has already addressed these questions in the interim between its Festo decision and the Supreme Court Festo opinion. For example, narrowing may occur when amending an original claim (Pall Corp. v. PTI Technologies Inc., 259 F.3d 1383 (Fed. Cir. 2001)), when including limitations from a dependent claim in an independent claim (Pioneer Magnetics, Inc. v. Micro Linear Corp., 238 F.3d 1341 (Fed. Cir. 2001)) or when submitting a new, narrower claim (Mycogen Plant Science Inc. v. Monsanto Co., on reh’g, 261 F.3d 1345 (Fed. Cir. 2001)). The estoppel effect of narrowing amendment may also be created even as to an unamended claim where a similar limitation was added to a parallel claim, thereby surrendering subject matter to overcome a rejection. Intermatic, Inc. v. The Lamson & Sessions Co., 273 F.3d 1355 (Fed. Cir. 2001).
The Federal Circuit also appears to be inclined to find that any narrowing amendment must be for some type of reason related to patentability. For example, in Pioneer Magnetics, the Federal Circuit found the amendment was related to patentability, even though the patentee presented some evidence that the relevant amendment to the independent claim was made inadvertently and was repetitive of a limitation appearing in a dependent claim. The problem facing applicants and prosecuting attorneys is that the only sure way to avoid estoppel due to a narrowing amendment seems to be to avoid narrowing the claim element in the first place.
The Supreme Court in Festo noted that a cosmetic amendment would not narrow the patent’s scope and thus would not raise the estoppel. Several decisions by the Federal Circuit have also suggested that amendments that only make express, a recitation of a feature that was already inherent in the original claim, is not a narrowing of the scope of the properly construed claim. TurboCare v. General Electric Co., 264 F.3d 1111 (Fed. Cir. 2001); Bose Corp. v. JBL, Inc., 274 F.3d 1354 (Fed. Cir. 2001) and Interactive Pictures Corp. v. Infinite Pictures, Inc., 274 F.3d 1371 (Fed. Cir. 2001).
However, patentees should expect to face an uphill battle when attempting to establish that the amendment was not narrowing. Aside from the normal claim construction evidence, the evidence most likely to sway the courts may be found in the record before the U.S. Patent and Trademark Office, to the extent the patentee has offered a contemporaneous rational in the remarks associated with amendment as to why the amendment does not narrow the claim.
The Rebuttable Presumption ~ If an estoppel is found, patentees will now be required to overcome a presumption of no equivalence by proving that the alleged equivalent falls within the scope of what is now permitted by the Supreme Court. It is expected that the prosecution history will often provide the best evidence on this point. Hence, it is more important than ever that patent prosecutors make every effort to both maximize the literal scope of coverage and at the same time optimize the record to support a position on equivalents that the patentee may want to take in the later litigation. Prosecuting attorneys may now face the prospect that during the litigation, they will be asked to explain why she amended the claims the way they did and why she did not use some hypothetical language supplied by defendant’s counsel that would have literally covered the accused product.
The Critical Date ~ When attempting to rebut the presumption, it remains for later decisions to determine which of the dates discussed by the court, the application or the amendment date, is most critical.
Foreseeability ~ As to "unforeseeability," it appears that the alleged equivalent would need to be either unknown or not recognized as an equivalent at the time of the prosecution. Alleged equivalents that are known at the time of prosecution are virtually eliminated since a person of skill in the art (as author of the claim and/or amendment) is presumed to have included such structures within the literal scope of the claim.
For those prosecuting patent applications, the question is what type of record to make to support an unforeseeability argument. Any indication in the record that other embodiments of a claim element were considered, but were ultimately excluded by the narrowing amendment, would seem to suggest actual foreseeability and should be avoided. In most instances, the need to narrow a claim arises in an effort to overcome prior art. In such cases, the best course may be to "bite the bullet" by simply focusing on what the claim does not cover, i.e., the applied prior art, and, thereby, attempt to minimize the damage.
Tangential Relationship ~ The Supreme Court held that when the patentee shows that the rationale underlying the amendment bears "no more than a tangential relation to the equivalent in question," estoppel should not bar equivalence. However, no guidance is provided as to what might qualify as a "tangential relationship."
However, as the courts increasingly focus on the patent itself and its prosecution history, success in this area may be more likely if the applicant creates a clear rationale for each amendment, recognizing the risk that presenting any such explanation will likely preempt any argument as to the existence of an estoppel in the first instance.