Federal Circuit Reverses PTAB Finding Of Obviousness
On November 04, 2021, the Court of Appeals for the Federal Circuit (CAFC) reversed the Patent Trial and Appeal Board’s (PTAB’s) holding that a patent claim was obvious, rejecting both the PTAB’s finding that the prior art disclosed all claim limitations and the PTAB’s finding that the combination of references would result in a reasonable expectation of success. University of Strathclyde v. Clear-Vu Lighting LLC, No. 2020-2243 (Fed. Cir. Nov. 04, 2021).
Obviousness is a question of law based on underlying questions of fact. A determination of obviousness requires that “all claimed limitations are disclosed in the prior art,” PAR Pharm., Inc. v. TWI Pharms., Inc., 773 F.3d 1186, 1194 (Fed. Cir. 2014), and that “a person of ordinary skill in the art would have been motivated to combine or modify the teachings in the prior art and would have had a reasonable expectation of success in doing so.” Regents of Univ. of Cal. v. Broad Inst., Inc., 903 F.3d 1286, 1291 (Fed. Cir. 2018). These requirements are questions of fact that the CAFC must review for substantial evidence. See Consumer Prods., Inc. v. Lighting Sci. Grp. Corp., 955 F.3d 16, 22 (Fed. Cir. 2020).
This appeal originated from an inter partes review petitioned for by Clear-Vu Lighting to invalidate U.S. Patent No. 9,839,706. The University of Strathclyde is the holder of the patent, claiming, in relevant part, a method for disinfecting surfaces by inactivating one or more pathogenic Gram-positive bacteria, said method comprising exposing the one or more pathogenic Gram-positive bacteria to visible light without using a photosensitizer, wherein a portion of the visible light that inactivates the one or more pathogenic Gram-positive bacteria consists of wavelengths in the range 400-420 nm. A photosensitizer is a chemical used to prime bacteria to produce porphyrins, which then cause these bacteria to be inactivated when exposed to light. Wavelengths in the range 400-420 nm are a subset of blue light.
The PTAB found that the claim was obvious based on two prior art articles about exposing bacteria to blue light. In the first article, scientists sought to determine the effects of a combination of blue light and the photosensitizer δ-aminolevulinic acid (ALA) by growing pathogenic Gram-positive bacteria on sets of agars either with or without ALA. The bacteria were then exposed to blue light and the relative inactivation was measured. Bacteria in both sets of agars were inactivated, but because the agar used contained riboflavin, which is also a photosensitizer, this was not sufficient to anticipate the claim. In the second article, the scientists exposed the bacteria to blue light without any photosensitizer but were unable to show inactivation.
The PTAB reasoned that the dispute was whether the prior art teaches exposing bacteria to light without using a photosensitizer and concluded that the two articles combined disclosed this limitation. The PTAB also found that a person of ordinary skill in the art would have had a reasonable expectation of inactivating bacteria using blue light without a photosensitizer because the claim merely required a non-zero amount of inactivation, the first article taught that increasing the dose of light resulted in increasing rates of inactivation, and a person having ordinary skill in the art would know that the bacteria naturally produce some porphyrins which could make them sensitive to blue light at some unknown level.
The CAFC rejected the PTAB’s reasoning and found that the dispute was whether the prior art teaches inactivating the claimed bacteria without using a photosensitizer. It therefore was not enough for the first article to teach inactivating bacteria with blue light and the second article to teach exposing bacteria to blue light without the photosensitizer. To teach every limitation as the doctrine of obviousness requires, one of the articles would have to have shown inactivating the bacteria without the photosensitizer.
Moreover, the CAFC dismissed the PTAB’s reasoning that a person having ordinary skill in the art would expect success as pure conjecture relying on hindsight. Because one article contained no information about the inactivation of the bacteria without a photosensitizer and the second article’s findings were directly contrary to the expectation of success, there was no evidence in the prior art of this expectation. The only evidence presented was therefore the uncontradicted testimony of Strathclyde’s expert, who opined that success could not be expected.
Having found that the record lacked substantial evidence to support the PTAB’s decision, the CAFC reversed the decision of obviousness.