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Specification Must Clearly Link Structure to Function of Means-Plus- Function Limitations

September 22, 2003

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Last Month at the Federal Circuit - October 2003

Judges: Clevenger (author), Schall, and Newman (dissenting)

In Medical Instrumentation and Diagnostics Corp. v. Elekta AB, No. 03-0132 (Fed. Cir. Sept. 22, 2003), the Federal Circuit concluded that there was no evidence to indicate that a person skilled in the art would not understand from the specification that a claimed “means for converting” structure corresponding to a “means for converting” claim limitation would include software. Accordingly, the Federal Circuit reversed the district court’s denial of JMOL of noninfringement of U.S. Patent No. 5,099,846 (“the ’846 patent”) and its continuation, U.S. Patent No. 5,398,684 (“the ‘684 patent”), and reversed the district court’s grant of SJ of no invalidity.

Medical Instrumentation and Diagnostics Corporation (“MIDCO”) owns the ‘846 and ‘684 patents, which relate to a system for planning surgical treatment using a presentation of images from multiple scanning sources. In 1997, MIDCO filed a patent-infringement suit against Elekta AB and others (collectively “Elekta”). Elekta counterclaimed for noninfringement and invalidity. After a Markman hearing, the district court granted MIDCO’s motion for partial SJ that its patents were not invalid. After a jury trial that awarded MIDCO $16 million in damages, the district court denied Elekta’s motions for JMOL of noninfringement.

MIDCO asserted claim 1 of the ‘684 patent and claim 9 of the ‘846 patent. The claimconstruction issues for both claims concerned the limitation “means for converting said plurality of images into a selected format.” There was no dispute that this element fell under 35 U.S.C. § 112, ¶ 6. The Federal Circuit agreed with the district court that the function of the “means for converting” is the converting of the acquired images into a particular selected format. The Federal Circuit also agreed with the district court that the structure corresponding to the function of converting includes the framegrabber and the computer video processor (“CVP”) disclosed in the patents. The Federal Circuit disagreed, however, with the district court’s identification of software for digital-to-digital conversion as an additional corresponding structure for the function.

The Federal Circuit disagreed with the inquiry applied by the district court, namely, whether one of skill in the art would have simply been able to write a software program to perform the claimed function. Rather, the Federal Circuit reasoned, § 112, ¶ 6, requires that a particular structure be clearly linked in the specification with the claimed function in order to qualify as corresponding structure.

The Court first looked to the specification of the ‘846 and ‘684 patents. It determined that an “Image Format Conversion” box in Figure 1 of the patents does not depict structure because it illustrates the steps of the method of the invention, not the structure of the apparatus. Likewise, the Federal Circuit determined that the text in the written description describing Figure 1 of the patents does not describe structure but only describes steps of the method of the invention. The Federal Circuit rejected the argument that a reference to software for “image editing” corresponds to structure for the conversion function, concluding that there is no evidence that one of skill in the art would understand the phrase “image editing” as a reference to the function of converting images into a selected digital format. Further, although the patents state that “[o]ther programs used in practicing the invention, such as image manipulation programs, are either commercially available or within the skill of practitioners in the programming arts,” ‘684 patent, column 12, lines 26-27, the Federal Circuit argued that this statement in no way links software to the function of converting images to a selected format. The Court reasoned that it is not enough simply to list a certain structure in the specification; that structure must also be clearly linked to a claimed function in order to be a corresponding structure.

The Federal Circuit also considered the prosecution history of the patents but determined that there is also nothing there to provide the required link. Because MIDCO had conceded noninfringement if the Court ruled against it on the claimconstruction issue, the Court reversed the judgment of infringement and remanded for entry of judgment in favor of Elekta.

As to validity, the Federal Circuit determined that Elekta’s expert testimony was sufficient to raise a genuine issue of invalidity. Elekta brought forth numerous references that allegedly either anticipated or rendered obvious the claimed invention. The Federal Circuit reasoned that Elekta’s expert quoted the particular portions of the references that were relevant for each of the claim limitations and did not simply make conclusory statements of invalidity. Further, the Federal Circuit determined that there was sufficient evidence to show the presence or absence of a motivation to combine references in an obviousness determination. Therefore, the Federal Circuit reversed the district court’s grant of SJ of no invalidity.

Judge Newman dissented, noting that the specification states that the computer-managed functions are conducted by software, thus providing sufficient structure for the function of counting and commenting. Judge Newman commented that the majority has created inappropriate conditions for computer-based inventions.