Charles R. Ducker Jr. and George P. Kobler
Copyright 2004
As it appears in the June 2004 Newsletter of the IP Section of the Alabama State Bar (Vol. 1, Issue 2).
Background
The Festo [1] decision, handed down by the Supreme Court in 2002, affects virtually every issued patent, every patent license, all pending patent litigation, and all pending patent applications. It was a seminal decision dealing with the doctrine of equivalents that was originally created in the 1950 Supreme Court case of Graver Tank & Mfg. Co. v. Linde Air Prod. Co. [2] to thwart an accused patent infringer who was not literally infringing every element of an issued patent claim. The doctrine of equivalents was intended for use by plaintiffs where an accused infringer had changed only a minor or insubstantial detail of the invention while retaining its essential identity. In other words, the doctrine could be invoked if the infringing device performs substantially the same function in substantially the same manner to accomplish substantially the same result.
While a powerful tool for prospectively broadening the scope of protection for the patent holder, the Supreme Court has also held that the doctrine of equivalents may be checked by prosecution history estoppel: You may not invoke the doctrine of equivalents for subject matter relinquished during the prosecution of a patent application. In Festo, the Supreme Court held that generally any amendment that narrows the scope of a patent claim for any reason related to patentability gives rise to a rebuttable presumption that prosecution history estoppel may operate as to the amended claim element [3]. Even voluntary amendments or amendments for which no clear reason is established in the file wrapper history of the application create a prosecution history estoppel. And in accordance with the Supreme Court's Festo ruling, the doctrine of equivalents would typically be barred for those amended claim elements. Festo set forth that the presumption of estoppel as to an equivalent may be rebutted upon a showing that the equivalent could not reasonably have been described at the time the amendment was made, the equivalent was tangential to the purpose of the amendment, or the equivalent was not foreseeable at the time of the amendment.
Recent Case Activity
Recently a number of patent cases have made their way through the Court of Appeals for the Federal Circuit and that addressed the doctrine of equivalents and prosecution history estoppel. These cases, Festo's children, are beginning to define the post- Festo realm for the patent prosecutor and patent prosecution in general. Glaxo Wellcome, Inc. v. Impax Laboratories, Inc., No. 03-1013, decided January 29, 2004, involves Glaxo Wellcome's (Glaxo) patent on a sustained release formulation of their Wellbutrin SR depression treatment and Zyban® drug for smoking cessation.
Glaxo's US Patent No. 5,452,798 (the '798 patent) claims a controlled sustained release tablet containing an admixture of bupropion hydrochloride and hydroxypropyl methylcellulose (HPMC). Many of the claims as originally filed, however, did not recite HPMC as a limitation. During prosecution, the Examiner rejected the claims that did not recite HPMC for lack of enablement under 35 U.S.C. § 112, ¶ 1. Glaxo amended those claims to include HPMC to overcome the rejection.
Impax Laboratories, Inc. (Impax), a manufacturer of generic pharmaceuticals, filed two Abbreviated New Drug Applications (ANDAs) with the US Food and Drug Administration (FDA), one proposing a generic substitute for Wellbutrin®SR, and the other proposing a generic substitute for Zyban®. In both ANDAs, Impax made a certification that its sustained release formulation did not infringe Glaxo's 798 patent. The sustained release agent in Impax's proposed composition was not HPMC, but hydroxypropyl cellulose (HPC). As a result, Glaxo could not enforce its patent on a claim of literal infringement, but could challenge such filings under the Doctrine of Equivalents. Upon hearing of Impax's ANDA filings, Glaxo commenced an infringement action in California. In a motion for summary judgment, Impax argued that the narrowing amendment to recite only HPMC and triggered the rebuttable presumption that Glaxo is estopped from reclaiming HPC. Glaxo attempted to counter the presumption by arguing that HPC was not foreseeable as an equivalent at the time of the amendment.
When the application was filed, Glaxo failed to include HPC as a possible time-release agent in its formulation, likely because the use of HPC had not been tested. The court noted that Glaxo could not have amended its claims to include HPC or it would have been rejected as claiming new matter. Nonetheless, the court disagreed with Glaxo that HPC was not foreseeable when the amendment was filed citing evidence it concluded sufficient to show that one skilled in the art could have reasonably been expected to draft a claim to literally encompass HPC.
Additionally, Glaxo argued that because the patent applicant did not argue that HPMC was critical to the enablement of the 798 claims, the principals of argument-based estoppel should not apply to any of its claims. In fact the Examiner initiated the arguments giving rise to the estoppel, however, the court held that prosecution history estoppel is "not limited to the applicant's own words, but may embrace as well the applicant's responses to the examiner's actions. If the patentee does not rebut an examiner's comment or acquiesces to an examiner's request, the patentee's unambiguous acts or omissions can create an estoppel."
Practical Effect
In the wake of Festo and its children, the last-minute patent application may become a thing of the past. Only after a thorough search of the prior art and an exhaustive interview with the inventor(s) to educate the patent draftsperson on the technology to which the invention pertains should a patent application be drafted. All such drafts must include as many different sets of claims of varying scope as practicable. Such a practice will allow for the cancellation of individual claims or sets of claims and the submission of new claims, rather than risk what could be considered a narrowing amendment under Festo . This additional review, evaluation, and preparation will increase both the time and cost of obtaining a patent, a burden felt more by individual inventors, start-ups and emerging companies than by large established companies.
Glaxo Wellcome confirms that even where an equivalent claim element is not known at the time of filing of an application but becomes known by the time of an amendment to a claim, the proper course for the practitioner is to file a new continuation application seeking protection for the equivalent or to see it lost to the prohibition of prosecution history estoppel. Arguably, this would also require an additional search of the prior art before making any amendments to ensure no newly known equivalents are forsaken. Either action, the filing of a new continuing application or a secondary state-of-the-art search prior to responding to a rejection will increase costs for the inventor(s) and the burden on the practitioner.
Further, Glaxo Wellcome observes that estoppel is not limited to patentee's own words but also embraces acquiescence in the examiner's comments and requests for amendments. Arguably, such an interpretation establishes a standard for all future responses to rejection where a colorable argument for patentability exists to pursue an appeal to the Board of Patent Appeals of the United States Patent and Trademark Office (USPTO). As the USPTO Board is already severely backlogged (it commonly takes years to decide an appeal), the practitioner is forced to balance the prejudice your client may suffer from delaying a patent grant by appealing and the cost and time involved in the appeal. Further, it is unclear whether acquiescing to gain allowance of a patent where a colorable argument for patentability existed for a non-amended claim constitutes malpractice.
In any event, the practitioner should always take care to scrutinize any examiner statements, whether in the form of an office action or a notice of allowance, and respond appropriately to reduce the risk of an opponent invoking prosecution history estoppel. As the patentee is responsible for its claims and the construction thereof, the practitioner must steer the prosecution of the application to increase the possibility the patent provide the greatest expected benefit to its owner.
Conclusion
Festo and its children, including Glaxo Wellcome, have established a higher standard of care for the patent practitioner in both the preparation and prosecution of a patent application. The assurance of a well researched and even better drafted application with numerous sets of claims of varying scope and the continuous search for newer, previously unknown equivalents have become required actions for the patent practitioner. These requirements will result in increased costs, both financial and temporal, for the preparation and prosecution of patent applications.
Notes
1. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 122 S.Ct. 1831, 152, L.Ed.2d 944 (2002). [Back to text.]
2. 339 U.S. 605, 85 USPQ 328 (1950). [Back to text.]
3. The Court held in Festo that a "patentee's decision to narrow his claims through amendment may be presumed to be a general disclaimer of the territory between the original claim and the amended claim." Id. at 741 The Court also stated that a "patentee might rebut the presumption that estoppel bars a claim equivalence." To do so, "the patentee must show 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." Id. [Back to text.]
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Copyright 2004 Charles R. Ducker Jr. and George P. Kobler