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Micro Chemical, Inc. v. Great Plains Chemical Co., Inc., No. 98-1393, 1999 U.S. App. LEXIS 24843, (Fed. Cir. Oct. 6, 1999).




Whether apparatus or methods "means-plus-function" claims, as limited by 35 U.S.C. 112 6 are restricted only to the structures described in the preferred embodiment.


No. Means-plus-function claims are limited by the function claimed in the specifications and the structure necessary to perform that function.


Micro Chemical, Inc., owns United States Patent No. 4,733,971 ("the '971 patent"), that discloses devices and methods for weighing, dispensing, and delivering micro-ingredients such as vitamins and medicines into livestock feed. Micro Chemical, Inc. filed suit against Lextron, Inc. for infringement of the '971 patent. Micro Chemical also sought to hold Lextron's president, Robert Hummel, personally liable for inducement to infringe. Micro Chemical, Inc. appealed the verdict from the United States District Court for the District of Colorado, that the accused device does not infringe the '971 patent, and that Hummel was not personally liable. The Federal Circuit reversed the district court's judgment as to the non-infringement of both the method and apparatus claims at issue, but affirmed the summary judgment releasing Hummel from personal liability.

The district court characterized the disputed "weighing means" elements, for determining the weights of selected additives, of the apparatus claims as "means-plus-function" elements under 35 U.S.C. 112 6. The court then looked only to the preferred embodiment specifications to limit the structural elements of the device claimed in the '971 patent. The district court also determined that the method claims at issue were not step-plus-function claims within the meaning of 35 U.S.C. 112 6 and limited the methods claimed to that of the preferred embodiment. In addition, the district court, in construing both apparatus and method claims, determined that the patentee disavowed the "weigh-dump" microingredient dispensing method of the prior art. The district court therefore held that Lextron's machine had neither identity of function nor equivalent structure of the accused device to infringe literally. The Federal Circuit reviewed the district court's claim construction de novo.

The Federal Circuit reiterated that when the term "means" appears in a claim element associated with a function, there is a presumption of means-plus-function treatment under 35 U.S.C. 112 6. As claims within the scope of 112 6 are limited to the specific acts described in the specifications and their equivalents, claims that fall outside 112 6 can be broader in scope. Interpreting claims under 35 U.S.C. 112 6 requires both identification of the claimed function and identification of the structure in the written description necessary to perform that function. The disputed apparatus claims involved "means-plus-function" language and properly invoked 112 6 treatment. The Federal Circuit held that the method claims were infringed literally because the '971 patent specifications described a preferred embodiment and several alternative embodiments for dispensing microingredients into feed. The district court therefore improperly limited the method of dispensing to that described by the preferred embodiment.

The Court did not address the issue of whether the district court's determination that the method claims were not in step-plus-function form was correct since the method claims were literally infringed.

The Court also held that Lextron's president was not personally liable for inducing infringement because he did not know his actions would induce infringement. He also took reasonable steps to avoid infringement by seeking the advice of counsel when designing the accused machine.


Prepared by the liibulletin-patent Editorial Board.

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