Primos, Inc. v. Hunter's Specialties, Inc.

Court of Appeals for the Federal Circuit
451 F.3d 841 (2006)

ELI5:

Rule of Law:

Prosecution history estoppel does not bar the application of the doctrine of equivalents when the rationale for a claim amendment is merely tangential to the equivalent in question. Additionally, a claim term should not be construed in a way that would exclude a preferred embodiment depicted in the patent's specification.

Facts:

Primos, Inc. held U.S. Patents 5,520,567 ('567) and 5,415,578 ('578) for a diaphragm mouth call used by hunters.
The '578 patent claims a mouth call with a 'plate' extending over a membrane.
During patent prosecution, Primos amended the '578 patent claim to specify that the plate must be 'differentially spaced' above the membrane to distinguish it from prior art where a structure sat directly on the membrane.
Hunter's Specialties, Inc., a competitor, manufactured and sold a similar mouth call called the 'Tone Trough.'
The Tone Trough device did not have a 'plate' but instead featured a 'dome' that was also differentially spaced above the membrane.

Procedural Posture:

Primos, Inc. sued Hunter's Specialties, Inc. and David Forbes in the U.S. District Court for the Northern District of Iowa for patent infringement.
The district court denied the parties' cross-motions for summary judgment.
Following a Markman hearing, the district court construed the disputed claim term 'engaging' to mean 'to come into contact with.'
The court denied a subsequent summary judgment motion by Hunter's Specialties that argued prosecution history estoppel barred the doctrine of equivalents claim.
The district court granted Primos's pre-trial motion to exclude a prior art device, the 'Aluminum Flap Call,' from evidence.
After a jury trial, the jury found Hunter's Specialties' device literally infringed the '567 patent and infringed the '578 patent under the doctrine of equivalents.
The jury also found willful infringement by Hunter's Specialties and inducement of infringement by David Forbes.
The district court denied motions by Hunter's Specialties for judgment as a matter of law (JMOL) and for a new trial.
Hunter's Specialties, Inc. and David Forbes (appellants) appealed the final judgment to the U.S. Court of Appeals for the Federal Circuit, with Primos, Inc. as the appellee.

Premium Content

Subscribe to Lexplug to view the complete brief

You're viewing a preview with Rule of Law, Facts, and Procedural Posture

Issue:

Does prosecution history estoppel prevent a patentee from claiming infringement under the doctrine of equivalents where the claim was amended for reasons of patentability, but the rationale for the amendment is only tangentially related to the accused infringing equivalent?

Opinions:

Majority - Louri, Circuit Judge

No, prosecution history estoppel does not prevent a patentee from claiming infringement under the doctrine of equivalents in this circumstance. The court held that the presumption of surrender can be overcome if the rationale underlying the amendment bears no more than a tangential relation to the equivalent in question. Here, the patentee amended the claim to add the 'differentially spaced' limitation to distinguish its invention from a prior art device where a structure was positioned directly on the membrane. Because the accused Tone Trough's 'dome' was also spaced above the membrane, the territory surrendered by the amendment (non-spaced structures) was not at issue. Therefore, the reason for the amendment was merely tangential to the accused equivalent (a spaced dome vs. a spaced plate), and prosecution history estoppel did not bar the infringement claim under the doctrine of equivalents. The court also affirmed that finding a 'dome' equivalent to a 'plate' did not vitiate the claim limitation under the all limitations rule, as it was an insubstantial change.

Analysis:

This decision provides a significant application of the Supreme Court's ruling in Festo, particularly clarifying the 'tangential relation' exception to prosecution history estoppel. It establishes that the focus of the estoppel inquiry is on the specific subject matter the patentee surrendered to overcome a prior art rejection. If an accused equivalent does not fall within that surrendered subject matter, the estoppel will not apply. This allows patentees to retain some scope under the doctrine of equivalents even after making a narrowing amendment, preventing competitors from making merely colorable changes that avoid literal infringement but still fall outside the specific reason for the amendment.

Gunnerbot

AI-powered case assistant

Loaded: Primos, Inc. v. Hunter's Specialties, Inc. (2006)

Try: "What was the holding?" or "Explain the dissent"