motivation to combine : CAFC Alert

Ramification of Silence in Prosecution History and Reminder on Formulating Effective Obviousness Arguments

| November 17, 2023


Decided: September 21, 2023

Before Reyna, Stoll, and Stark.  Opinion by Reyna.


The CAFC held that motivation to combine references is supported by substantial evidence including the patent prosecution history where relevancy of certain prior art, similar to an asserted reference in the IPR, was not contested by the applicant. The CAFC also rejected the patent owner’s arguments on lack of requisite findings on reasonable expectation of success, where such findings can be implied from express findings on motivation to combine as the two issues are interrelated to each other.


Elekta’s U.S. Patent No. 7,295,648 (the “’648 patent”) pertains to ionizing radiation treatment. The technology is designed to deliver therapeutic radiation, such as one created by a linear accelerator or “linac,” to a target area of a patient such as brain tumors for treatment purposes.  The ‘648 patent discloses that the linac, because of its great weight, requires a suitable structure to support the device while allowing a wide range of movement to focus the radiation precisely, leading to a challenge in implementing the linac-based system for treating highly sensitive, complex areas as with neurosurgery.

Representative claim 1 of the ‘648 patent recites:

A device for treating a patient with ionising radiation comprising:
a ring-shaped support, on which is provided a mount,
a radiation source attached to the mount;
the support being rotateable about an axis coincident with the centre of the ring;
the source being attached to the mount via a rotateable union having a an axis of rotation axis which is non-parallel to the support axis;
wherein the rotation axis of the mount passes through the support axis of the support and the radiation source is collimated so as to produce a beam which passes through the co-incidence of the rotation and support axes.

In the underlying inter partes review, the final written decision concluded, among other things, that claim 1 of the ’648 patent is obvious over a combination of Grady and Ruchala.  In essence, Grady teaches an X-ray imaging device having a sophisticated rotatable support structure similar to that recited in the body of claim 1, whereas Ruchala teaches a linac-based radiation device for treating tumors, which may correspond to “treating a patient with ionising radiation” of claim 1.

On appeal, the CAFC addressed Elekta’s three main arguments regarding obviousness of claim 1: (1) “the Board’s findings on a motivation to combine are unsupported by substantial evidence”; (2) “the Board failed to make any findings, explicit or implicit, on a reasonable expectation of success”; and (3) “even had the Board made such findings, those findings are not supported by substantial evidence.”  The CAFC reviewed the Board’s legal conclusions de novo and its factual findings for substantial evidence. 

  • Substantial evidence for the motivation to combine

Elekta argued that substantial evidence was lacking with the Board’s finding of a motivation to combine the references.  In particular, Elekta asserted that no motivation would have existed for a skilled artisan to combine Grady and Ruchala, one disclosing “radiation imagery” and the other for “radiation therapy,” where incorporating Ruchala’s linac radiation into Grady’s imaging system would not improve its imagery function in any aspect, whilst the linac’s heavy weight would hamper precision and control, thereby “render[ing] the device essentially inoperable.”

The Board’s obviousness conclusion relies on, among other findings, its review of the prosecution of the ’648 patent, wherein “patents directed to imaging devices were cited, and were not distinguished based on an argument that imaging devices were not relevant art,” along with the pertinent field being framed in the IPR as one that “includes the engineering design of sturdy mechanical apparatus[es] capable of rotationally manipulating heavy devices in three dimensions oriented in a variety of approach angles with high geometrical accuracy, in the context of the radiation imaging and radiation therapy environment.”

The CAFC held that there was substantial evidence for the motivation to combine. Specifically, the CAFC noted that such evidence includes the prosecution history of the ’648 patent, in which Elekta “notably did not argue that prior art references directed to imaging devices were not relevant art.”  The CAFC concluded that such failure to distinguish imaging radiation prior art during the patent prosecution, along with the asserted references and an expert testimony pointing to benefits of combining imagery and therapeutic radiation functions, substantially support the motivation to combine.

  • Findings on the reasonable expectation of success

Elekta argued that the Board’s obviousness determination was devoid of any findings on reasonable expectation of success.

The CAFC disagreed, finding that a sufficient, implicit finding was made as to the reasonable expectation of success.  The CAFC contrasted findings of reasonable expectation of success, which “can be implicit,” with those of motivation to combine, which must be “explicit.” Although an explicit finding would be usually required to support determinations made by the Board, the CAFC points to its precedent where the Board’s rejection of a patent owner’s motivation to combine argument based on teaching away constituted an implicit finding of a reasonable expectation of success, as the latter could be “reasonably discern[ed]” in the Board’s findings on “other, intertwined arguments.”

The CAFC noted that Elekta’s own arguments on the motivation to combine and the reasonable expectation of success presented before the Board were “blended”: Elekta essentially asserted that the suggested combination, lacking precision and control due to the device’s heavy weight, would fail to serve its intended purposes so as to negate motivation to combine, and consequently, would also negate reasonable expectation of success.  As such, the CAFC held that by making express findings on the motivation to combine, the Board adequately made an implicit finding on Elekta’s argument on reasonable expectation of success.

  • Substantial evidence for the reasonable expectation of success

Elekta argued that substantial evidence was lacking in the Board’s findings, if any, on reasonable expectation of success.

The CAFC succinctly rejected the argument. The CAFC noted that the evidence establishing a motivation to combine may—but not always—establish a finding of reasonable expectation of success.  And that was the case with the present appeal, where “the arguments and evidence of reasonable expectation of success are the same for motivation to combine.”


            This case presents an interesting situation pointing to one potential ramification of prosecution history made by silence: A failure to object to the scope of pertinent art during patent prosecution undercuts the patent owner’s argument in attacking the motivation to combine, where the asserted prior art is arguably from a disparate field.  It is important to consider potential benefits and downsides of presenting or not presenting certain arguments during prosecution.

            Another takeaway is the importance of formulating non-obviousness arguments on an issue-by-issue basis even if interrelated issues are involved; doing so would help keep the analysis of reasonable expectation of success from being comingled with the issues of motivation to combine.

General industry skepticism may not be sufficient by itself to preclude a finding of motivation to combine

| August 2, 2022

Auris Health, Inc. v. Intuitive Surgical Operations, Inc.

Decided: April 29, 2022

Prost (author), Dyke, and Reyna (dissenting)


The Federal Circuit rejected the PTAB’s obviousness decision by holding that general industry skepticism is not relevant to the question of obviousness.


            In 2018, Intuitive Surgical sued Auris Health for patent infringement of U.S. Patent No. 8,142,447 (“the ’447 patent”).

The ’447 patent

            This patent is directed to robotic surgery systems. 

            The ’447 patent describes “an improvement over Intuitive’s earlier robotic surgery systems, which allow surgeons to remotely manipulate surgical tools using a controller.”

            The ’447 patent attempts to solve problems (doctors must swap out various surgical instruments and this step could be tricky in a robotic surgical system where space is limited, different ranges of motion must be calibrated for different surgical instruments, and time is need to interchange those instruments) in the surgery via a robotic system with a servo-pulley mechanism so that doctors could swap out surgical instruments and reduce surgery time, improve safety, and increase reliability of the system.


            The PTAB determined that the prior art references asserted by Aurie – Smith and Faraz – disclosed each limitation of the claims in the ’447 patent.

            The only remaining issue is whether a skilled artisan would have motivated to combine these two references.

            Smith discloses “a robotic surgical system that uses an exoskeleton controller, worn by a clinician, to remotely manipulate a pair of robotic arms, each of which holds a surgical instrument.”  Smith discloses that the clinician may direct an assistant to relocate the arms as necessary.

            Faraz is directed an adjustable support stand that holds surgical instruments.  Faraz discloses that its stand “may enable a surgeon to perform surgery with fewer assistants” because its stand “can support multiple surgical implements while [they] are being moved” and “can also provide support for a surgeon’s arms during long or complicated surgery.”

            Auris argued that a skilled artisan would be motivated to combine these references to decrease the number of assistants necessary for surgery.

            Intuitive argued that a skilled artisan would not be motivated to combine these references because “surgeons were skeptical about performing robotic surgery in the first place, [so] there would have been no reason to further complicate Smith’s already complex robotic surgical system with [Faraz’s] roboticized surgical stand.”

            The PTAB agreed with Intuitive that there is no motivation to combine these references because there is skepticism at the time of the invention for using robotic systems during surgery in the first place.

Federal Circuit

            The Federal Circuit held that general industry skepticism cannot, by itself, preclude a finding of motivation to combine.

            The Federal Circuit noted that the evidence of skepticism must be specific to the invention, not generic to the field and that Intuitive provided not case law to suggest that the PTAB can rely on generic industry skepticism to find a lack of motivation of combine.

            The Federal Circuit held that the PTAB was wrong to exclusively rely on Intuitive’s expert testimony that “there was great skepticism for performing telesurgery” at the time of the invention and, as a result, a skilled artisan “would not have been compelled to complicate Smith’s system further.”

            Therefore, the Federal Circuit remand for further consideration of the parties’ motivation-to-combine evidence.


            Judge Reyna noted that the PTAB’s determination that Auris failed to show a motivation to combine is adequately supported by substantial evidence and was not contrary to our law on obviousness.

            While Judge Reyna agreed that skilled artisans’ general skepticism toward robotic surgery, by itself, could be insufficient to negate a motivation to combine, he disagreed that it could never support a finding of no motivation to combine.

            Judge Reyna believes that the majority’s inflexible and rigid rule appears to be in tension with the central thrust of KSR (rejecting the “rigid approach of the Court of Appeals” and articulating an “expansive and flexible approach” of determining obviousness).


  • General industry skepticism may not be sufficient by itself to preclude a finding of motivation to combine.
  • Specific evidence of industry skepticism related to a specific combination of references might contribute to finding a lack of motivation to combine.

To Combine or not to Combine

| April 16, 2018

Ex parte Tesseir et al.

October 2, 2014

Before PTAB APJ Panel: Kerins, Staicovici & Woods.

Summary:  The Board affirmed many of the rejections in this appeal of a Final Rejection.  But the Board found that there was no motivation to support the obviousness rejection of claim 13 and therefore reversed the rejection of that claim.



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