## Facts

- Primos, Inc. owned two patents for a diaphragm “mouth call” game-call device placed entirely inside a hunter’s mouth to simulate animal sounds.
- The patented device used a vibrating membrane and a “shelf or plate” above at least part of the membrane to maintain spacing from the tongue, resist pressure, and improve sound control.
- Hunter’s Specialties sold a competing mouth call that used a dome-shaped structure over the membrane rather than a flat plate.
- Primos sued for infringement in the Northern District of Iowa, asserting literal infringement of the ’567 patent and infringement of the ’578 patent under the doctrine of equivalents.
- During prosecution of the ’578 patent, claim amendments added “length” and “differential spacing” limitations relating to the plate’s structure and spacing above the membrane.
- After claim construction and a jury trial, the district court entered judgment for Primos, including literal infringement (and willfulness/inducement) as to the ’567 patent and infringement under the doctrine of equivalents as to the ’578 patent, and denied Hunter’s motion for a new trial.

## Issues

1. Whether the district court correctly construed the ’567 patent term “engaging,” supporting the jury’s finding of literal infringement.
2. Whether infringement under the doctrine of equivalents for the ’578 patent was barred by prosecution history estoppel or the all-limitations rule, given the claim amendments and the accused dome structure.
3. Whether the district court abused its discretion in evidentiary rulings and in giving an adverse-inference instruction, warranting a new trial.

## Decision

- The Federal Circuit affirmed the construction of “engaging” and therefore affirmed the judgment of literal infringement of the ’567 patent.
- The court affirmed the finding of infringement under the doctrine of equivalents for the ’578 patent, holding that prosecution history estoppel did not bar equivalence and that the all-limitations rule was not violated.
- The court affirmed denial of a new trial, finding no abuse of discretion in excluding evidence and no prejudicial error in the adverse-inference instruction.
- The district court’s judgment was affirmed in all respects.

## Legal Principles

- Claim construction grounded in the intrinsic record governs infringement; affirmance of construction generally sustains a supported jury finding of literal infringement.
- Doctrine of equivalents may apply where an accused element performs substantially the same function, in substantially the same way, to achieve substantially the same result as the claimed element.
- Narrowing amendments can trigger prosecution history estoppel, but estoppel bars equivalents only to the extent the prosecution record shows a clear surrender of the particular equivalent at issue.
- The all-limitations rule bars equivalence only when an asserted equivalent would effectively read a claim limitation out of the claim; it is not violated merely because the accused structure differs in form (e.g., dome versus plate) if the limitation remains meaningfully satisfied by an insubstantial variation.
- Evidentiary exclusions and adverse-inference instructions are reviewed for abuse of discretion; reversal requires prejudicial error.

## Conclusion

The Federal Circuit upheld findings that Hunter’s product literally infringed the ’567 patent and infringed the ’578 patent under the doctrine of equivalents, rejecting prosecution-history and all-limitations defenses and leaving intact the trial court’s evidentiary rulings and denial of a new trial.


Primos, Inc. v. Hunter’s Specialties, Inc., 451 F.3d 841 (Fed. Cir. 2006)