by Dennis Crouch
University of Strathclyde v. Clear-Vu Lighting LLC (Fed. Cir. 2021)
The Federal Circuit’s recent Strathclyde decision focuses on claim limitations that require the invention to be effective. One oddity of the decision is that the court (and the PTAB below) treat the limitation with full respect just like any other structural limitation.
Researchers at Strathclyde conducted a set of experiments and found that certain blue light (~405 nm wavelength) was effective at inactivating methicillin-resistant Staphylococcus aureus (MRSA) even at low intensity and without first applying a photosensitizing agent. The resulting method claim focuses on this discovery and includes one simple step — inactivating MRSA bacteria by exposing it to blue (400-420 nm) light and without using a photosensitizer. U.S. Patent No. 9,839,706.
It turns out that the prior art (Nitzan) discloses a series of experiments using the same blue light and testing its effectiveness at inactivating MRSA bacteria. The tests compared the response of untreated bacteria as compared with bacteria treated with a photosensitizing agent.
Nitzan’s prior art procedure was identical to that claimed by Strathclyde with only one key difference. Nitzan found that none of the MRSA bacteria were killed by the blue light without first applying a photosensitizing agent. The patentee (Strathclyde) later used the same frequency of blue light without a photosensitizing agent, and this time it worked to inactivate MRSA.
Thus, the only difference between Strathclyde’s claimed invention and the prior art is the requirement that the invention actually work to “inactivate” the bacteria.
1. A method for disinfecting … by inactivating … pathogenic Gram-positive bacteria … comprising exposing the … bacteria to visible light without using a photosensitizer … and wherein a portion of the visible light that inactivates the … bacteria consists of wavelengths in the range 400-420 nm. . .
Claim 1 of the ‘706 patent. Traditionally, a functional “resulting” or “whereby” clause is only given patentable weight if it provides some structure or acts that are used to define the invention itself. For instance, in drug treatment cases, “effective amount” limitations can be used to define the amount of drug given to the patient. Here, however, the “inactivating” limitation does not appear to change any particular structure or acts and so, in my view, does not add patentable weight.
The invention here seems quite important–treating MRSA using otherwise harmless light and without potentially toxic chemical pre-treatment. And, Strathclyde should be able to patent the advances that it introduced that actually contributed to the success. I suspect that Strathclyde did do something different than Nitzan in terms of light intensity or frequency of treatment, or some other conditions. But, the claims here do not require a person of skill in the art to do anything different than Nitzan except achieve a different outcome. Clear-Vu did not make these patentable weight arguments to the Federal Circuit and the Federal Circuit did not raise them sua sponte.
This case was before the PTAB via IPR. The PTAB originally sided with the patent challenge Clear-Vu. The PTAB concluded that Nitzan taught all of the elements of the invention except for actual success at killing MRSA. However, another reference Ashkenazi suggested ways that someone of skill in the art would find obvious in terms of increasing light intensity to kill some of the bacteria. Thus, the PTAB found the claims obvious.
On appeal, the Federal Circuit has reversed and reinstated the patent. The court noted the complete absence of any prior art indicating that blue light alone would kill MRSA without a chemical pre-treatment to sensitize the bacteria. Further, there was evidence that such an approach would fail. Still Strathclyde succeeded and, according to the Federal Circuit, deserve its patent.
On this record, we conclude that no reasonable fact finder could have found that the combination of Ashkenazi and Nitzan discloses inactivating one or more Gram-positive bacteria without using a photosensitizer. The Board’s finding to the contrary is not supported by substantial evidence.
Prior art treated MRSA with blue light, but it didn't work to kill the bacteria.
Inventor treated MRSA with blue light and it worked to kill the bacteria.
Can Inventor patent "effectively treating MRSA with blue light"? (Claims cover prior art except require success).
— Dennis Crouch (@patentlyo) November 5, 2021