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The Federal Circuit in University of Strathclyde v. Clear-Vu-Lighting, 2020-2243 (Nov. 4, 2021) reminded practitioners and the PTAB that factual findings – including the presence of claim elements in prior art references and whether a person of skill (POSA) would have had a reasonable expectation of success in combining references – must be supported by substantial evidence.

In the Final Written Decision for IPR2019-00431, the Board held that Petitioner-Appellee Clear-Vu Lighting demonstrated that Patent Owner-Appellant University of Strathclyde’s patent claims in U.S. Pat. No. 9,839,706 directed to the inactivation of bacteria through the use of blue light without a photosensitizer was rendered obvious by two references (Ashkenazi in view of Nitzan).  Ashkenazi demonstrated that the use of blue light together with photosensitizers (either δ-aminolevulinic acid (ALA) or riboflavin) inactivated bacteria.  Ashkenazi also concluded that substances like ALA that promoted intracellular porphyrins achieve better inactivation results.  Nitzan followed on this teaching and examined ALA and the use of exogenous porphyrins together with blue light as a tool for inactivation.  Nitzan used four sets of examples, two with ALA (like Ashkenazi) and two without, one of these with added exogenous porphyrins.  The results of the two non-ALA cultures showed little inactivation.

Clear-Vu argued that the teaching of Ashkenazi, although showing only examples of the use of blue light together with a photosensitizer to inactivate bacteria, provided teaching that increasing the “dose” of blue light (intensity or time) had the effect of causing greater inactivation.  Clear-Vu argued that a POSA would combine the methodology of Ashkenazi with the non-ALA cultures of Nitzan, thus providing a blue light inactivation process without photosensitizers.  Citing Petitioner’s expert, the Board agreed.  As the Federal Circuit noted, “the Board summarily dismissed Strathclyde’s arguments” that the absence of photosensitizers in examples demonstrating inactivation was fatal.  Slip Op. at 8.  Similarly, the Board found that a POSA would have had a reasonable expectation of success of inactivating MRSA (a bacterium of interest) using blue light without a photosensitizer.

Under the substantial evidence standard applied to factual findings of the Board, the court asks “whether a reasonable fact finder could have arrived at the agency’s decision” and “involves examination of the record as a whole, taking into account evidence that both justifies and detracts from an agency’s decision.”  See Slip Op. at 9 (quoting OSI Pharms., LLC v. Apotex, Inc., 939 F.3d 1375, 1381-82 (Fed. Cir. 2019) (quoting In re Gartside, 203 F.3d 1305, 1312 (Fed. Cir. 2000))).

The Court first turned to the Board’s finding that all elements of the claims are found in the cited references.  The claims all require that the bacteria be exposed to 400-420 nm blue light without using a photosensitizer and that the bacteria are inactivated as a result.  Clear-Vu agreed that Ashkenazi’s examples all used a photosensitizer.  In Nitzan, although two of the bacteria cultures had no photosensitizer, the blue light application had no inactivation.  The Court held that no substantial evidence supported the Board’s finding because no inactivation had been shown.

With regard to reasonable expectation of success, the Board held that a POSA would reasonably expect success from a combination of Ashkenazi and Nitzan even though neither reference showed such inactivation without the presence of a photosensitizer.  The Court found no substantial evidence supporting that finding.  In part, the finding was based in diminishing earlier findings by Nitzan, namely that increasing endogenous porphyrins alone did not inactivate bacteria when also exposed to blue light.  The Board noted that the evidence should be viewed as a very narrow teaching, but without further reasoning.  The Court further noted that the unrebutted testimony of Strathclyde’s expert stated just the opposite, namely that the reasonable expectation would be of failure, not success because of the Nitzan experiments.

The key takeaway from University of Strathclyde is that where an element is missing from a reference, imputing its existence without substantial evidence will meet with reversal.  Similarly, as the Court noted, “where the prior art evidences only failures to achieve that at which the inventors succeeded, no reasonable fact finder could find an expectation of success based on the teachings of that same prior art.”  Slip Op. at 19.

If you have questions, please contact Philip L. Hirschhorn at or (215)-965-1257.

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