On November 4, 2021, the Federal Circuit reversed a final written decision of the Patent Trial and Appeal Board (“PTAB”) finding claims obvious under 35 U.S.C. § 103. The panel held that neither the PTAB’s finding that the prior art disclosed all claim limitations nor its finding of a reasonable expectation of success was supported by substantial evidence.

Concerning a patent for inactivating MRSA and other Gram-positive bacteria, the claims required both exposing the claimed Gram-positive bacteria to 400–420 nm blue light without using a photosensitizer and that the bacteria are inactivated as a result. Although the references used 400-420 nm blue light, one of the references used a photosensitizer and the other did not successfully achieve inactivation.

On the subject of a reasonable expectation of success, the Federal Circuit reaffirmed that absolute predictability of success is not required, only a reasonable expectation. Nevertheless, in this case, “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.” In so holding, the Federal Circuit noted that “not only is there a complete lack of evidence in the record that any bacteria were inactivated after exposure to 407–420 nm blue light without using a photosensitizer, there is also evidence showing that others had failed to inactivate MRSA—one of the claimed Gram-positive bacteria—without using a photosensitizer, despite experimenting with different light doses and different wavelength ranges of blue light,” which undermines a finding of a reasonable expectation of success. The Federal Circuit also found that other findings of the PTAB were only supported by “pure conjecture coupled with hindsight reliance on the teachings” in the patent at issue.

Based on this precedent, patent owners should consider presenting evidence of failures of the prior art, when it is available, to rebut obviousness challenges.