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Another case on the limits of means-plus-function claiming(08/27/10)
An earlier news item on this web site discussed “means plus function” claiming, in which a limitation is stated as a means for performing a particular function. An accused product, in order to infringe such a claim, must contain structure that performs that function and is identical to or equivalent to the structure disclosed in the specification of the patent in suit. The structure in the accused product is an equivalent to the corresponding structure in the patent only if the accused structure performs the same function in “substantially the same way” and with “substantially the same result.” This last point is illustrated in a precedential decision the Court of Appeals for the Federal Circuit handed down on August 27, 2010. In General Protecht Group, Inc. v. Wenzhou Trimone Science & Technology Electric Co., Ltd., a claim to a ground fault interrupter wiring device was not infringed because the limitation “latching means releaseably retaining said conducting member in said first position” was not met by the accused ground fault circuit interrupters because the structure disclosed in the patent for performing the releaseably retaining function was mechanical and the accused interrupters used magnets to perform the releaseably retaining function. The result might have been different if the patent had been drafted to simply claim a “latch,” because experts testified that “magnets were well known as latches.”
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