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IP Alert: Teachings in the Art Undercut PTAB's Reasonable Expectation of Success Finding

November 18, 2021

On November 4, in University of Strathclyde v. Clear-Vu Lighting, evidence from outside the asserted references tipped the Federal Circuit toward finding a lack of reasonable expectation of success. The Federal Circuit reversed the Patent Trial and Appeal Board (PTAB), because the PTAB lacked evidentiary support for finding a reasonable expectation of success when combining the two asserted prior art references.

The University’s patent claimed methods for inactivating certain antibiotic-resistant bacteria using narrow wavelengths of blue light. Prior art methods, as described by the University’s patent, required applying a photosensitizer to the bacteria, such that the bacteria would be inactivated when exposed to visible light. The University’s patent, however, claimed methods for disinfecting by exposing the bacteria to the light without using a photosensitizer.

Clear-Vu filed a petition for inter partes review, asserting grounds of anticipation based on a 2004 article by Nitzen, and obviousness based on an article by Ashkenazi combined with the Nitzan article. The PTAB found that Nitzan did not anticipate, but that the combination of Ashkenazi and Nitzan invalidated the challenged claims.

On appeal, the University challenged the PTAB’s obviousness determination on two grounds: (1) the PTAB erred in finding that the combination of the two cited references taught that bacteria could be inactivated without using a photosensitizer and (2) the PTAB erred because its finding of a reasonable expectation of success was not supported by substantial evidence.

Regarding the first challenge, the Federal Circuit rejected the PTAB’s finding that the combined Ashkenazi and Nitzan references would have taught that bacteria could be inactivated without using a photosensitizer. According to the Federal Circuit, Nitzan did not disclose successfully inactivating bacteria without a photosensitizer. And the University had presented unrebutted evidence to the PTAB showing that each of Ashkenazi’s experiments had grown bacteria in the presence of riboflavin, a known photosensitizer.

Regarding the second challenge, on reasonable expectation of success, the Federal Circuit looked to teachings in the art as a whole—not merely the cited references. The court rejected the PTAB’s invalidity finding that the teachings of Ashkenazi and Nitzan would have provided evidence of a reasonable expectation of success. Neither reference disclosed inactivating bacteria without using a photosensitizer. The court supplemented its finding by looking at teachings from a third article by Nitzan, published in 1999. The teachings in the Nitzan 1999 article were “directly contrary” to the PTAB’s finding of what a skilled artisan would have reasonably expected, because Nitzan 1999 found no effect on bacteria exposed to light without added photosensitizers. Thus, the court found not only a complete lack of evidence in the record to support the PTAB’s reasonable expectation of success determination, but also, through the use of the Nitzan 1999 reference, that a skilled artisan would have expected failure of the claimed invention.

The Federal Circuit also reiterated the importance of evaluating reasonable expectation of  success from the subjective perspective of the skilled artisan—not based on the objective success of the inventor. The Federal Circuit found the PTAB’s analysis was based on “pure conjecture coupled with hindsight reliance” because it was improperly based on teachings in the challenged patent. Clear-Vu had argued that teachings in the challenged patent established physical phenomena that, although unknown prior to the inventor’s discovery, showed the asserted combination of Ashkenazi and Nitzan would have been successful. The Federal Circuit rejected this argument. The court noted that in an obviousness determination “[w]hat matters is the path that the person of ordinary skill in the art would have followed, as evidenced by the pertinent prior art,” not the inventor’s own path.

This opinion reinforces that when evaluating whether an ordinarily skilled artisan would have a reasonable expectation of success, teachings throughout the known art may be relevant. Well-reasoned expert testimony and teachings within the art may establish whether a skilled artisan would have expected success in building upon teachings in the cited references. Further, teachings in the patent being challenged are hindsight evidence that cannot serve as the basis for finding a reasonable expectation of success.

For more information on this holding, please contact Fitch Even partner David A. Gosse or associate Irfan Hassam-Malani, authors of this alert.


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