## Facts

- Alan Amron and his company, Talk to Me Products, Inc. (TTMP), held rights to U.S. Patent No. 4,239,129, covering a toy water gun that pressurizes water stored in a tank located within the gun’s body and includes certain electrical light-and-sound features.
- The asserted patent claim required, among other limitations, an “elongated housing having a chamber therein for a liquid,” describing a liquid-storage chamber located inside the housing.
- Larami Corporation manufactured and sold “SUPER SOAKER” toy water guns that pressurized water using a hand-operated pump and controlled discharge with a trigger-operated valve mechanism.
- Unlike the patented design, Larami’s SUPER SOAKER products used a water reservoir that was prominently located outside the gun’s housing, mounted above the barrel, and detachable from the gun.
- Larami sued TTMP seeking, among other relief, a declaration of noninfringement of the ’129 patent; TTMP counterclaimed for patent infringement.
- Larami moved for partial summary judgment seeking a ruling of noninfringement and judgment against TTMP’s infringement counterclaim based on the “chamber therein” limitation.

## Issues

1. Whether Larami’s SUPER SOAKER water guns literally infringed a claim requiring an “elongated housing having a chamber therein for a liquid” when the accused products stored water in an external, detachable reservoir rather than a chamber inside the housing.
2. Whether TTMP could avoid summary judgment by showing infringement under the doctrine of equivalents based on the SUPER SOAKER’s external, detachable reservoir allegedly serving as the equivalent of the claimed internal liquid chamber.

## Decision

- The court granted Larami’s motion for partial summary judgment of noninfringement.
- The court held there was no literal infringement because the accused SUPER SOAKER products did not include the claimed limitation of a liquid chamber within the elongated housing.
- The court held TTMP did not raise a triable issue under the doctrine of equivalents because the external, detachable reservoir was not the substantial equivalent of the claim’s internal liquid chamber.
- As a result, the court entered judgment for Larami on the noninfringement issues addressed by the motion and against TTMP’s infringement counterclaim to the same extent.

## Legal Principles

- Patent infringement analysis begins with claim construction; interpreting claim language is a question of law for the court.
- Literal infringement requires the accused product to include every limitation of the asserted claim; if any one limitation is missing, literal infringement fails.
- The doctrine of equivalents is applied on an element-by-element basis; the patentee must show the substantial equivalent of each claim limitation, not merely similarity of the overall product.
- The doctrine of equivalents cannot be used to effectively remove or rewrite a specific claim limitation (such as an “internal” chamber) to capture a different structure (such as an “external, detachable” reservoir).
- Summary judgment is appropriate where the claim language and undisputed product structure show a missing claim element, and the nonmoving party lacks evidence from which a reasonable factfinder could find equivalence for that element.

## Conclusion

The court granted partial summary judgment of noninfringement because the ’129 patent claim required a liquid chamber located within the gun’s elongated housing, while Larami’s SUPER SOAKER water guns used an external, detachable reservoir; that structural difference defeated literal infringement and, on this record, also defeated TTMP’s doctrine-of-equivalents theory.


Larami Corp. v. Amron, 27 U.S.P.Q.2d 1280 (1993)