Ramification of Silence in Prosecution History and Reminder on Formulating Effective Obviousness Arguments
| November 17, 2023
ELEKTA LIMITED v. ZAP SURGICAL SYSTEMS, INC.
Decided: September 21, 2023
Before Reyna, Stoll, and Stark. Opinion by Reyna.
Summary
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.
Details
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.”
Takeaways
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.
Tags: motivation to combine > prosecution history > Reasonable Expectation of Success
