Federal Circuit Affirms PTAB Final Written Decision Finding Fluorescence Detection Patent Not Unpatentable as Obvious
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  • Federal Circuit Affirms PTAB Final Written Decision Finding Fluorescence Detection Patent Not Unpatentable as Obvious

    On April 24, 2023, the United States Court of Appeals for the Federal Circuit (“CAFC”) issued an opinion affirming the decision of the U.S. Patent and Trademark Office Patent Trial and Appeal Board (“Board”) finding that Leica Microsystems, Inc. (“Leica”) failed to show that the claims of a patent directed to a fluorescence detection system were unpatentable as obvious.  Leica Microsystems, Inc. v. Regents of the University of Michigan, Appeal No. 22-1445 (Fed. Cir. Apr. 24, 2023).

    The Regents of the University of Michigan (the “Regents”) own a patent on a fluorescence detection system that detects light that is emitted from a sample after it is struck with an excitation light.  The system uses ultrafast white light optical pulses to excite fluorophores and a detector to detect the emitted light.

    Leica petitioned for inter partes review (“IPR”) of the patent, asserting that the claims would have been obvious over prior art reference “Folestad,” which discloses a method of analyzing a turbid pharmaceutical sample (such as a tablet) using white light from a laser excitation source, in view of other references, including “Wittmershaus,” which describes a method for analyzing fluorophores in chlorophyll from spinach leaves using a fluorescence detection system.

    In its Final Written Decision, the Board found that Leica had failed to show an adequate rationale for combining Folestad with, e.g., Wittmershaus.  In doing so, the Board rejected Leica’s expert testimony as conclusory and lacking support and further held that there was no evidence that Folestad would have provided any improvement/benefit over Wittmershaus.  The Board also rejected Leica’s attempt to show that substituting one sample for another in the same system was routine, and it held that the record lacked evidence regarding whether one of skill in the art would have configured Folestad’s system to actually measure fluorescence.

    On appeal, Leica made three arguments:  (1) the Board’s obviousness analysis was overly rigid because it focused too heavily on the references themselves and failed to consider the background knowledge of one of skill in the art; (2) the Board’s finding that sample substitution was not simple was not supported by substantial evidence because the Board improperly focused on unclaimed sample preparation techniques, which, even if relevant, would have been routine; and (3) the claimed invention is merely a new use of Folestad’s pre-existing system, which renders it not inventive.

    The CAFC agreed with the Regents that the Board properly found that Leica’s proposed combination of Folestad with Wittmershaus required replacing Folestad’s teachings of detection of transmitted or reflected radiation with Wittmershaus’s detection of fluorescence, and that there was a lack of evidence regarding how to modify Folestad to actually measure fluorescence, as claimed in the challenged patent.  The CAFC further explained that the Board was well within its discretion to weigh the parties’ expert testimony and make a determination based on that evidence.  Accordingly, the CAFC affirmed the Board’s final written decision.