Federal Circuit Affirms Noninfringement Finding on Claim Construction Grounds in Fluorescence Detection Patent Case

The U.S. Court of Appeals for the Federal Circuit (CAFC) issued a decision Friday affirming a grant of summary judgment of noninfringement entered by the U.S. District Court for the Northern District of California. The appeal, brought by the Regents of the University of Michigan against Leica Microsystems, Inc., concerned the construction of claim language describing a “supercontinuum” white light pulse used in fluorescence detection technology.

The underlying patent, U.S. Patent No. 7,277,169, relates to fluorescence detection systems for samples containing fluorophores, a type of fluorescent marker. The invention uses a supercontinuum white light laser to excite fluorophores so that a variety of targets can be detected simultaneously. The ‘169 patent distinguishes the claimed invention from prior art that used optical filters to remove portions of the light spectrum before it reached a sample. Each independent claim requires “a supercontinuum white light pulse comprising an entire spectrum of white light” that excites the fluorophores present in the sample.

Michigan filed a lawsuit against Leica in the district court, alleging that certain Leica products infringed the claims of the ‘169 patent. Leica moved for summary judgment, arguing that its accused products excited sample fluorophores using only several discrete, selected wavelengths filtered from a white light pulse before the light reached the sample, and that this did not meet the claims’ requirement of an entire spectrum of white light. Michigan disagreed, arguing that the claims did not require the entire spectrum of white light to reach the sample.

The district court, presided over by Judge William H. Orrick III, concluded that “the scope of the ‘said supercontinuum’ language necessarily refers to ‘a supercontinuum white light pulse comprising an entire spectrum of white light’ as what excites the fluorophores present in a sample.” The district court granted Leica’s motion, finding no genuine dispute that the accused products did not reach the scope of that claim language.

Michigan timely appealed, and the CAFC exercised jurisdiction under 28 U.S.C. Section 1295(a)(1). Since the noninfringement judgment turned solely on claim construction, the CAFC applied de novo review, following the standard set out in SanDisk Corp. v. Memorex Products, Inc. In reviewing the summary judgment ruling itself, the CAFC applied Ninth Circuit law, which requires viewing evidence in the light most favorable to the nonmoving party and determining whether genuine issues of material fact exist.

Michigan argued that the district court erred in construing the “said supercontinuum” terms, contending in its brief that the claims “[do] not impose any requirement on what light must physically reach the sample.” The CAFC found this position inconsistent with the plain language of the claims. Since the claims require the fluorophores of the sample to be excited by “said supercontinuum white light pulse,” the term “said” functions as an anaphoric phrase. As the district court explained, it refers back to the original clause where the term at issue appears. The CAFC therefore agreed that “the antecedent basis for ‘said supercontinuum white light pulse’ is a ‘supercontinuum white light pulse comprising an entire spectrum of white light.’” The CAFC also cited its earlier decision in Summit 6, LLC v. Samsung Electronics Co., which described claims using the term “said” as “anaphoric phrases, referring to the initial antecedent phrase.”

The Federal Circuit further noted that the claims distinguish between the entire supercontinuum and “a portion of said supercontinuum white light pulse.” According to the court, this distinction showed that Michigan knew how to draft a limitation covering only portions of the light spectrum and deliberately chose not to do so for the limitations at issue on appeal. The patent specification was also cited as indicating that the entire spectrum reaches the sample and as rejecting the use of filters.

In an amendment aimed at overcoming a prior art rejection, Michigan had stated that prior art reference Itoh “teaches selecting several discrete wavelengths from a white light continuous spectrum and using those discrete wavelengths, not the entire spectrum,” while asserting that “the present invention uses and claims the entire spectrum of the white light to simultaneously excite all the fluorophores.” The Federal Circuit found that Michigan repeatedly distinguished its invention from the prior art’s teaching of “discrete” and “selected” wavelengths during prosecution, and that these representations supported the district court’s claim construction.

The court also declined to review claim construction issues Michigan raised that were unrelated to the noninfringement judgment on appeal, citing Massachusetts Institute of Technology v. Abacus Software for the proposition that the court will not review “claim construction issues not implicated by the judgment.”

Since Michigan’s challenge to the summary judgment of noninfringement rested entirely on its challenge to the claim construction, and the CAFC adopted that construction, the court affirmed the summary judgment. The Federal Circuit stated it had considered Michigan’s remaining arguments and found them unpersuasive.

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