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Larami Corp. v. Amron

Citation. Larami Corp. v. Amron, 27 U.S.P.Q.2D (BNA) 1280, 1993)
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Brief Fact Summary.

Amron (Defendant), a manufacturer of toy water guns, claimed that Larami Corp. (Plaintiff), another manufacturer, had infringed on its patent.

Synopsis of Rule of Law.

Literal infringement of a patent cannot be proven if the accused product is missing even one element of the claim.


Larami Corp. (Plaintiff) manufactured toy water guns and held patents for four different models of toy guns. Amron (Defendant) claimed that Plaintiff’s guns infringed on a patent it held for toy water guns that included light and noise components. Claiming that there was neither literal infringement nor any substantial equivalence of all the elements in the other patents, Plaintiff moved for partial summary judgment of noninfringement of Defendant’s patent and for partial summary judgment on Defendant’s counterclaim for infringement of its patent.


Does the absence of even a single element of a patent’s claim from the accused product mean there can be no finding of literal infringement?


(Reed, J.) Yes. Literal infringement of a patent cannot be proven if the accused product is missing even one element of the claim. Also, in order to show infringement under the doctrine of equivalents, the patent owner must prove that the accused product has the “substantial equivalent†of every limitation or element of a patent claim. In patent cases, summary judgment is appropriate where the accused product does not literally infringe the patent and where the patent owner does not gather evidence that is sufficient to satisfy the legal standard for infringement under the doctrine of equivalents. Since Larami’s (Plaintiff) toy water pistol uses an external, detachable water reservoir that was found to be a dramatic improvement over the traditional design, it could not be held to be substantially equivalent to Amron’s (Defendant) claim in its patent. Motion granted.



A patent owner’s right to exclude others from making, using or selling the patented invention is defined and limited by the language in that patent’s claims. Therefore, in this case, the court was limited to interpreting the actual words used to describe the toy guns. Claim interpretation is a question of law for the court to decide.

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