Decoding Reasonable Expectation of Success in Obviousness Determination

Babak Akhlaghi

In order for an invention to be patentable under the U.S. patent regime, it must be both novel and non-obvious.  Novelty, in this context, refers to whether the invention is considered to be in the "public domain" under the law. The test for novelty is defined in 35 U.S.C. §102.  The invention is considered to fail this test if a single prior art reference, such as a previous patent or publication, shows the same invention. 

Even if the invention is deemed novel, it must also satisfy the requirement of non-obviousness to be patentable. The test for non-obviousness is outlined in 35 U.S.C. §103, which aims to prevent the granting of patents for inventions that merely make an insignificant departure from what is already known in the prior art. An invention fails this test if a combination of two or more prior art references teaches the same invention.  Since the obviousness test often involves combining references, the Examiner must demonstrate that a person skilled in the relevant field (1) would have been motivated to make such a combination, and (2) would have had a reasonable expectation of success in arriving at the claimed invention. In Elekta Ltd. v. Zap Surgical Systems, the Federal Circuit held that in an obviousness determination, a reasonable expectation of success finding can be made implicitly unlike a motivation to combine finding, which requires an explicit analysis. Therefore, it is advisable to present separate arguments for motivation to combine and reasonable expectation of success, preferably using different supporting points.

In Elekta Ltd. v. Zap Surgical Systems – A Detailed Analysis of the Case

 In Elekta Ltd. v. Zap Surgical Systems, No. 21-1985 (Fed. Cir. Sept. 21, 2023) (Reyna, Stoll, Stark JJ.), the Federal Circuit held that in an obviousness determination, a reasonable expectation of success finding can be made implicitly unlike a motivation to combine finding, which requires an explicit analysis. 

 Elekta Limited (“Elekta”) is the owner of U.S. Patent No. 7,295,648 (“the ‘648 Patent”), directed to a device for treating patients with ionizing radiation. The device, which utilizes a linear accelerator (or "linac") on concentric rings, delivers targeted beams of ionizing radiation to specific areas on patients.

 On September 27, 2019, ZAP Surgical Systems, Inc. (“ZAP”) filed a petition for inter partes review (“IPR”) with the U.S. Patent and Trademark Office, challenging the claims of the '648 patent. The IPR asserted, among other grounds, that the claims of the ‘648 patent are obvious over 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”).

Grady reveals an X-ray tube mounted on a sliding arm connected to a rotating support. Ruchala, on the other hand, describes a linac-based tomotherapy treatment system where the linac and detector rotate around the patient while they remain still, targeting tumors.

 On March 30, 2021, the Board issued its decision, concluding that all the challenged claims were unpatentable as obvious over Grady and Ruchala.  Elekta appealed, asserting that (1) a skilled artisan would not have been motivated to combine Grady with Ruchala, and (2) would not have had a reasonable expectation of success in combining the Grady device with the linac described in Ruchala. 

 Obviousness requires a finding that a skilled artisan (1) would have been motivated to combine the teachings of prior art in such a way that the combination discloses the claimed limitations and (2) would have had a reasonable expectation of success. 

Motivation to Combine

Elekta contended that it would not make sense for someone skilled in the field to replace Grady's X-ray imaging source with Ruchala's linac therapeutic source. The X-ray imaging source is designed for imaging and cannot handle the heavy and potentially harmful effects of the linac source.

 The Board acknowledged Elekta's argument but ultimately disagreed. It found that skilled artisans were aware of heavy linac sources during the relevant time period and that robotic arms could effectively handle their weight. This conclusion was reinforced by the fact that during the patent application examination process, the Examiner cited imaging devices to reject the claims of the ‘684 patent, and the patentee did not argue that these references were irrelevant.  Furthermore, Ruchala's teachings support the idea that combining imaging with radiation delivery is advantageous because it improves the accuracy of radiation treatment and verifies the received dose. For these reasons, the Federal Circuit held that there was substantial evidence to support the Board's finding that skilled artisans would be motivated to combine Grady's device with Ruchala's linac.

Reasonable Expectations of Success

Elekta also argued that the Board erred as a matter of law because it failed to articulate any findings on reasonable expectation of success.  The Federal Circuit disagreed, holding that unlike a motivation to combine determination, which requires explicit analysis, a reasonable expectation of success can be implied. The Court acknowledged that this may seem contradictory to the Administrative Procedure Act (APA), which requires the Board to explain its decisions in detail, including the factual findings and rationale. However, in this case, the Court found no contradiction because the Board implicitly addressed the reasonable expectation of success by considering and addressing the other intertwined argument, a motivation to combine.

 Reasonable expectation of success refers to the likelihood of success in combining references to meet the limitations of the claimed invention. The Court noted that Elekta used some of the same arguments for both motivation to combine and reasonable expectation of success in front of the Board. For example, when asked during oral argument what reasonable expectation of success arguments it made before the Board, Elekta reiterated its argument that a skilled person in the art would be deterred to replace Grady’s X-ray source with heavy linacs which requires precision in radiation therapy targeting. 

Conclusion 

Given these circumstances, the Federal Circuit concluded it can be reasonably inferred that the Board considered and implicitly addressed the reasonable expectation of success based on the arguments and evidence presented on motivation to combine.  Therefore, the Federal Circuit affirmed the Board’s obviousness rejection. 

 
Practice Tip: The Administrative Procedure Act ("APA") mandates that the Patent Office must clearly explain its decisions, including the specific factual findings and reasoning behind them. In this case, the Board didn’t provide any explicit explanation as to why one of ordinary skill in the art would have had a reasonable expectation of success in combining the references. However, because the patent owner combined their arguments for this issue with the arguments for motivation to combine, the Board's detailed findings on motivation to combine were deemed to implicitly address this issue. Therefore, to increase the chances of success at the Board and on appeal, it is advisable for a patentee to present separate arguments for motivation to combine and reasonable expectation of success, preferably using different supporting points.