Background
The University of Michigan sued Leica Microsystems for allegedly infringing U.S. Patent No. 7,277,169, which covers fluorescence-detection systems that use a supercontinuum white-light laser to excite fluorescent markers in a sample. Each independent claim requires “a supercontinuum white light pulse comprising an entire spectrum of white light” and states that “said” pulse excites the fluorophores.
Leica argued that its accused products used only several discrete wavelengths filtered from a white-light pulse before the light reached the sample. The Northern District of California construed the claims to require the entire spectrum of white light to excite the fluorophores and granted Leica summary judgment of noninfringement because no reasonable jury could find that Leica’s products met that limitation. Michigan appealed the claim construction and resulting judgment.
The Court’s Holding
The Federal Circuit affirmed. It held that the phrase “said supercontinuum white light pulse” refers back to its antecedent—a supercontinuum white-light pulse comprising an entire spectrum of white light. The claims therefore require the entire spectrum, rather than merely selected portions of it, to excite the fluorophores in the sample.
The claim language reinforced that construction by separately referring elsewhere to “a portion” of the pulse, showing that the patent drafter knew how to claim only part of the spectrum. The specification likewise indicated that the entire spectrum reaches the sample and distinguished systems using filters. Michigan’s prosecution statements also contrasted the claimed invention with prior art using discrete, selected wavelengths and represented that the invention used the entire spectrum to excite the fluorophores.
Because Michigan’s noninfringement challenge depended entirely on overturning that claim construction, the Federal Circuit affirmed summary judgment for Leica. The court declined to address constructions of other claim terms that were not implicated by the judgment.
Key Takeaways
- The anaphoric word “said” carried the full “entire spectrum of white light” limitation from the claim’s antecedent phrase.
- Contrasting claim language covering “a portion” of the pulse supported reading the disputed limitation to require the entire spectrum.
- The specification and Michigan’s prosecution statements confirmed that the claims excluded excitation using discrete wavelengths filtered from white light.
Why It Matters
The nonprecedential decision illustrates how antecedent language, distinctions among limitations within the same claim, and representations made to overcome prior art can collectively narrow claim scope. A patentee that distinguishes prior art by emphasizing use of an entire spectrum may be unable to recapture systems that use only selected wavelengths.
It also underscores that when an infringement appeal turns entirely on claim construction, affirmance of the construction can resolve noninfringement without a separate factual dispute requiring trial.