In Elekta Limited v. Zap Surgical Systems, Inc., No. 21-1985 (Fed. Cir. Sept. 21, 2023), the case addresses the interplay between findings related to motivation to combine and reasonable expectation of success in determining obviousness under 35 U.S.C. § 103. 

Background

Elekta Limited (“Elekta”) is the owner of U.S. Patent No. 7,295,648 (the “’648 patent), which discloses “a device for treating a patient with ionizing radiation for certain types of radiosurgery and radiation therapy.” “The invention uses a radiation source, e.g., a linear accelerator (referred to as a ‘linac’), mounted on a pair of concentric rings to deliver a beam of ionizing radiation to the targeted area on the patient.” 

The instant dispute between Elekta and ZAP Surgical Systems, Inc. (“ZAP”) stems from an IPR filed by Zap which challenged claims 1-4, 7-13, 16-18, 20, and 22-23 of the ’648 Patent. The Board instituted the IPR on April 1, 2020 and issued its final written decision on March 30, 2021. In the final written decision, the Board found all challenged claims of the ’648 patent obvious in light of the combination of U.S. Patent No. 4,649,560 (“Grady”) and a publication, K.J. Ruchala et al., Megavoltage CT image reconstruction during tomotherapy treatments, Phys. Med. Biol. 45, 3545-3362 (2000) (“Ruchala”). 

As described by the Federal Circuit, Grady discloses an X-ray tube mounted on a sliding arm connected to a rotating support that allows the arm to be rotated around a patient to take X-ray images. Ruchala discloses a “linac-based tomotherapy treatment system” wherein “‘the patient remains still, but the linac and detector rotate about the patient’ to deliver a treatment dose to the target tumor.” 

During the IPR, Elekta argued that a person of ordinary skill in the art would not have been motivated to combine, and would not have had a reasonable expectation of success in combining, the Grady device with the linac described in Ruchala, particularly in light of the fact that the Grady device was an imaging device, rather than a radiation device, and because the weight of the linac in Ruchala would render the Grady device inoperable, imprecise, and unsuitable for treatment. The Board disagreed and found a motivation to combine Grady with Ruchala, rendering the ’648 patent invalid due to obviousness. Elekta appealed the Board’s final written decision to the Federal Circuit.

Issues

On appeal, Elekta challenged the Board’s findings with respect to motivation to combine, arguing that it was not supported by substantial evidence. Elekta also argued that the Board failed to make any findings, either explicitly or implicitly, with respect to reasonable expectation of success, and even if such findings were made, that they were not supported by substantial evidence. Based on Elekta’s arguments, the Board considered the following issues:

1. Whether there was substantial evidence for the Board to find that a skilled artisan would have been motivated to combine the prior art references disclosing radiation imagery (Grady) with the references disclosing radiation therapy (Ruchala)?
2. Whether the Board erred as a matter of law because it failed to articulate any findings on reasonable expectation of success?
3. Whether, even if the Board made an implicit finding with respect to reasonable expectation of success, there was substantial evidence to support a finding that a skilled artisan would have reasonably expected to succeed in combining the asserted references?
4. Whether the proper burden of proof with respect to reasonable expectation of success is clear and convincing evidence or a preponderance of the evidence?

Holdings

1. There was substantial evidence to support the Board’s finding that a skilled artisan would have been motivated to combine the asserted prior art references.
2. In discussing motivation to combine, the Board made sufficient implicit findings to support its conclusion that a skilled artisan would have had a reasonable expectation of success in combining the asserted prior art references.
3. There was substantial evidence to support the Board’s finding that a skilled artisan would have had a reasonable expectation of success in combining the asserted prior art references.
4. The proper burden of proof with respect to reasonable expectation of success is preponderance of the evidence. See 35 U.S.C. § 316(e).

Reasoning

1) Elekta argued that no substantial evidence existed to support the Board’s motivation to combine finding because the linac device in Ruchala would not offer any improvement to the imaging capabilities of Grady and further that the Grady device does not “contemplate a heavy linac or account for the lack of precision that would result from the linac’s additional weight.” The Federal Circuit disagreed and pointed to the “the prosecution history of the ’648 patent, the teachings of the asserted prior art references, and the expert testimony of record” as evidence supporting the Board’s finding that a skilled artisan would have been motivated to combine the asserted prior art references.

The Federal Circuit credited the Board’s finding that during prosecution “the patentee notably did not argue that prior art references directed to imaging devices were not relevant art.” Further, the Federal Circuit noted that the prior art, specifically Ruchala and U.S. Patent No. 4,998,268 (“Winter”), describes the advantage of having a single device capable of imaging and delivering radiation, namely, more accurate radiation delivery. With respect to the weight of the linac, the Federal Circuit references the Board’s findings that “heavy linacs were known in the art during the pertinent period and that their weight could be adequately handled by robotic arms.” Finally, the Federal Circuit pointed to ZAP’s expert, who opined that combining the imaging apparatus with the treatment apparatus would eliminate the need to transfer the patient from one apparatus to the other and would reduce the patient’s exposure to radiation. 

Based on the above, the Federal Circuit found that substantial evidence existed to support the Board’s finding that a person of ordinary skill in the art would have been motivated to combine the imaging device of Grady with the radiation delivery device of Ruchala.

2) Elekta argued that the Board’s decision should be reversed because the Board failed to make any findings with respect to reasonable expectation of success. An obvious determination requires a motivation to combine prior art references and a reasonable expectation of success in doing so. See Regents of Univ. of California v. Broad Inst., Inc., 903 F.3d 1286, 1291 (Fed. Cir. 2018). The Federal Circuit explained that while the motivation to combine determination requires an explicit analysis, a finding of reasonable expectation of success can be implicit where the arguments and evidence on reasonable expectation of success are intertwined with those addressing motivation to combine. 

For example, Elekta argued that the proposed prior art combinations would lead to an inferior quality product, an inoperable device, and would teach away because the weight of the linac device would not be supported by the device disclosed in Grady. The Federal Circuit reasoned that Elekta’s arguments were addressed to both motivation to combine and reasonable expectation of success, and thus the Board did not err in implicitly addressing reasonable expectation of success by explicitly discussing motivation to combine, particularly where Elekta presented the arguments in a blended manner. On this basis, the Federal Circuit determined that the Board made sufficient implicit findings that a skilled artisan would have had a reasonable expectation of success in combining the prior art references.

3) Elekta argued that even if the Board made a proper implicit finding on reasonable expectation of success, there was not substantial evidence that could support a finding that a skilled artisan would have reasonably expected to succeed in combining the asserted references. In rejecting Elekta’s argument, the Federal Circuit again focused on the intertwined nature of the motivation to combine arguments and the arguments directed to reasonable expectation of success. While not always the case that a finding of motivation to combine establishes a reasonable expectation of success, where the evidence and arguments overlap, as they do here, the evidence establishing a motivation to combine may establish a finding of reasonable expectation of success.

As such, because the evidence with respect to motivation to combine was sufficient to support the Board’s finding on motivation to combine, the same arguments and evidence were sufficient with respect to reasonable expectation of success. 

4) The Federal Circuit quickly dismissed Elekta’s argument on the applicable burden of proof by citing 35 U.S.C. § 316(e), which provides that “[i]n an inter partes review instituted under this chapter, the petitioner shall have the burden of proving a proposition of unpatentability by a preponderance of the evidence.”