Description
The DOE is a judicial doctrine that permits a court to find infringement when an accused product or process falls outside the literal language of the claims but is equivalent to and differs only insubstantially from the claimed invention. The concept of something infringing when the accused product "performs substantially the same function in substantially the same way to obtain the same result" can be found as far back as Sanitary Refrigerator Co. v. Winters, 280 U.S. 30, 42 (1929).
Prosecution history can operate as a limit on DOE. "The doctrine of prosecution history estoppel limits the doctrine of equivalents when the applicant makes a narrowing amendment for purposes of patentability, or clearly and unmistakably surrenders subject matter by arguments made to the examiner." Salazar v. Procter & Gamble Co. (Fed. Cir. 2005). The rationale for this principle is that the patentee should not be allowed to gain through the DOE claim scope that it gave up during prosecution to obtain allowance of the claims. The panel will discuss the example of argument-based prosecution history estoppel found in Amgen Inc. v. Coherus Biosciences Inc. (Fed. Cir. 2019).
According to the U.S. Supreme Court in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co. (2002) (Festo VIII), a patentee can rebut the presumption that prosecution history estoppel applies if it shows that the patentee comes within one of three exceptions. These exceptions are: the equivalent was unforeseeable at the time of the application, the rationale underlying the amendment bears no more than a tangential relation to the equivalent in question, or another reason suggesting that the patentee could not be expected to describe the insubstantial substitute.
Listen as our authoritative panel examines the lessons from Federal Circuit decisions for practitioners arguing for or against the Festo exceptions and, more broadly, for or against applying the DOE. The panel will also discuss hypothetical-claim analysis, first applied in the Federal Circuit Wilson icosahedron golf ball case, and ensnarement, disclosure-dedication, and the all-limitations rule.
Presented By
Dr. Browning focuses on patent litigation and appeals. He has led teams as first chair at trial, at Markman proceedings, and on appeal. His litigation experience includes taking and cross examining witnesses at trial, briefing and arguing dispositive motions, drafting appellate briefs, and arguing cases on appeal. He has also managed day-to-day litigation activities in actions involving multiple parties. In addition, he advises clients on patent matters, including coordination of prosecution and U.S. and foreign litigation strategy.
Mr. Irving has 47 years of experience in the field of IP law. His practice includes due diligence, patent prosecution, reissue and reexamination, patent interferences, and counseling, including prelitigation, Orange Book listings of patents covering FDA-approved drugs, and infringement and validity analysis in the chemical fields, as well as litigation. He has served as lead counsel in many patent interferences.
Dr. Murphy focuses her practice on client counseling and patent prosecution for a range of clients. She prepares new patent applications, prosecutes U.S. and foreign applications, and represents applicants at appeals and oral hearings before the PTAB. She has experience in prosecuting inter partes and ex partes reexamination applications, reissue applications, and patent term extension applications for approved pharmaceuticals, including obtaining supplemental protection certificates in Europe.
Ms. O’Brien has more than 20 years of experience representing domestic and foreign clients of all sizes in patent procurement, litigation, and client counseling, with a particular emphasis on chemical, biochemical, and pharmaceutical technologies. Exemplary areas of her technical expertise include polymer chemistry; ceramics; glass; food chemistry; cosmetics; paper products; adhesives; and pharmaceutical products, including new chemical entities and formulations and novel solid forms, including polymorphs, cocrystals, and amorphous forms of compounds.
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This 90-minute webinar is eligible in most states for 1.5 CLE credits.
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Date + Time
- event
Monday, October 13, 2025
- schedule
1:00 p.m. ET./10:00 a.m. PT
I. Early DOE decisions; policy considerations
II. Estoppel
A. Argument-based
B. Amendment-based
III. Festo
A. Exceptions
1. The equivalent was unforeseeable at the time of the application
2. Tangential relation
3. An unreasonable expectation to describe the insubstantial substitute
IV. Hypothetical claims/ensnarement
V. Disclosure-dedication
VII. All-limitations rule
The panel will review these and other important issues:
- The reappearance of the Festo exceptions
- The return of ensnarement
- Best practices for drafting and prosecuting claims to minimize estoppel-preventing DOE arguments
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