On Feb. 5, 2016, in TriVascular, Inc. v. Samuels, the United States Court of Appeals for the Federal Circuit affirmed the written decision of the Patent Trial and Appeal Board (PTAB or "Board") of the United States Patent and Trademark Office (USPTO) in an Inter Partes Review (No. IPR2013-00493) of U.S. Patent No. 6,007,575 (the '575 patent). In particular, the court affirmed the Board's conclusion that the '575 patent was not invalid as being obvious over the prior art of record despite the Board's initial institution of the IPR based on obviousness grounds. The '575 patent, entitled "Inflatable intraluminal stent and method for affixing same within the human body," relates to inventions in the field of intraluminal stent technology, and particularly to a vascular stent for treating medical conditions which could cause either vascular stenosis or an aneurysm.

The '575 patent was filed by Dr. Shaun L.W. Samuels on June 6, 1997, and generally claims an intraluminal stent which can be affixed to a vascular wall by way of "an inflatable and deflatable cuff." The cuff enables the vascular stent to remain in place without requiring penetration of the vessel wall, as was taught in the prior art. To secure the cuff in place without penetrating the vessel wall, the invention provides:

… said friction-enhancing outer surface featuring inflatable protrusion(s) including at least one circumferential ridge disposed about the inflatable cuff, said friction-enhancing outer surface engaging the interior of the tubular structure without penetration to prevent the cuff from moving in a longitudinal direction with respect to the tubular structure when said cuff is in a fully inflated condition; (Claim 1, emphasis added.)

The '575 patent was granted in 1999, and in 2013 the patent owner sued TriVascular alleging infringement. In response, TriVascular filed a petition for inter partes review of the '575 patent. In its petition, TriVascular alleged, inter alia , that the '575 patent was obvious in light of Samuels' earlier patent, U.S. Patent No. 5,423,851 (the '851 patent), which disclosed an inflatable and deflatable cuff having "a plurality of individual barbs 18 which … engage the wall of a tubular structure within the body."

In its Institution Decision, the Board construed a key term, "circumferential ridge disposed about the inflatable cuff," to mean a "raised strip disposed circumferentially about the outer surface of the inflatable cuff." The Board stated that, based on this construction, "on the present record, we do not agree with Patent Owner's argument that Samuels '851 teaches away" from substituting the penetrating anchoring barbs taught in the reference with the circumferential ridges of the '575 patent. (Institution Decision, pg. 16, emphasis added.) The Board further stated that "on the present record, Patent Owner has not established that removing the barbs in Samuels '851 would destroy the objective of the reference or go against its basic teaching." (Id., emphasis added.) The Board concluded that "Petitioner has established a reasonable likelihood that it would prevail in showing that claim 1 is unpatentable as obvious over" the prior art of record, and was institutinginter partes review on the following two grounds: 1) obviousness over Samuels' '851 patent and U.S. Patent No. 5,423,745 to Todd et al. (Todd); and 2) obviousness over U.S. Patent No. 5,693,088 to Lazarus et al. (Lazarus) and Todd (Id., at 17).

Despite the Board's initial decision to institute inter partes review of the '575 patent, on Dec. 13, 2014, the Board issued a Final Written Decision, holding that TriVascular failed to meet its burden of demonstrating that the challenged claims were unpatentable over the applied art. In its final decision, the Board adopted Samuels' construction of "inflatable protrusions," as "protrusions that contain fluid and are themselves inflatable," rather than TriVascular's construction that "inflatable protrusions can be 'solid' structures such as barbs or[,] in the case of [] some of the prior art examples, solid circumferential ridges." (Petitioner's Reply.) Rejecting TriVascular's construction, the Board instead held that the '575 patent's "inflatable protrusions" were not disclosed by the prior art, nor would a skilled artisan have been motivated to combine the prior art in a manner that would read on the claims of the '575 patent. The Board also found that the prior art did not teach the "circumferential ridges" taught in the '575 patent at issue, based on its claim construction at institution, which did not permit the "circumferential ridges" to be made up of a series of discontinuous inflatable protrusions formed circumferentially about the cuff.

TriVascular appealed the Board's decision to the Federal Circuit, claiming that the Board erred: 1) in its construction of the term "circumferential ridges;" and 2) in its holding that TriVascular failed to demonstrate that the challenged claims of the '575 patent are invalid as obvious over the prior art. Regarding TriVascular's first contention, the court found no error in the Board's construction of the term "circumferential ridges" as requiring the ridges to be continuous. In particular, the court was satisfied with the Board's reliance on the written description of the '575 patent, which described a circumferential ridge as a raised strip "disposed about [the] circumference of outer surface 23 of inflatable cuff 17." The court also approved of the Board's reliance on a general purpose dictionary definition of "ridge" as "a raised strip (as of plowed ground)" to be in accord with the specification's description of a raised strip. Finally, the court agreed with the Board's finding that TriVascular's proposed construction of "circumferential" that would encompass discontinuous raised sections "does not inform the meaning of the term 'circumferential ridge.'"

Regarding TriVascular's second contention, the court found no error in the Board's ultimate decision that TriVascular had failed to demonstrate that the challenged claims of the '575 patent are invalid as obvious over the prior art despite TriVascular initially demonstrating a reasonable expectation of success in showing obviousness. TriVascular's argument in its appeal that the Board should not have changed its view of the patent's validity without clearly explaining why it had done so was summarily rejected by the court as a "misguided theme [which] pervades TriVascular's briefs." (Opinion, pg. 18.) The court explained as follows:

Contrary to TriVascular's assertions, the Board is not bound by any findings made in its Institution Decision. At that point, the Board is considering the matter preliminarily without the benefit of a full record. The Board is free to change its view of the merits after further development of the record, and should do so if convinced its initial inclinations were wrong. To conclude otherwise would collapse these two very different analyses into one, which we decline to do. (Id., emphasis in original.)

As the court pointed out, there is a significant difference between a petitioner's burden to establish a "reasonable likelihood of success" at institution, and actually proving invalidity by a preponderance of the evidence at trial. This is in line with the USPTO's own definition of the "reasonable likelihood of success" standard, which, as explained by Chief Administrative Judge James D. Smith, "allows for the exercise of discretion but encompasses a 50/50 chance" of success. By contrast, as explained in the Manual of Patent Examining Procedure (MPEP), when evaluating the patentability of a claim, "[t]he standard to be applied in all cases is the 'preponderance of the evidence' test. In other words, an examiner should reject a claim if, in view of the prior art and evidence of record, it is more likely than not that the claim is unpatentable." (MPEP, Section 706 – Rejection of Claims.)

The "preponderance of the evidence" standard is clearly a higher standard than the "reasonable likelihood of success" standard, and its implementation after institution of the IPR is appropriate given that the task of the Board is effectively the same as that of the original examiner: to determine the patentability of the claims in view of the prior art and evidence of record. These two distinct thresholds are codified in separate statutes: 35 U.S.C. §314(a) (standard for institution ofinter partes review is "reasonable likelihood that the petitioner would prevail with respect to at least one of the claims challenged in the petition"); and 35 U.S.C. §316(e) ("the petitioner shall have the burden of proving a proposition of unpatentability by a preponderance of the evidence").

As the court explained: "The Board's findings in its Final Written Decision were thus not inconsistent with those in its Institution Decision; they were made under a qualitatively different standard." (Opinion, pg. 19, emphasis added.) While the Board had initially decided that "on the present record" in front of it at the time of institution there was a reasonable likelihood that TriVascular would prevail, Samuels later provided expert testimony and additional evidence which persuaded the Board that there was insufficient motivation to combine the prior art references as TriVascular had insisted. According to the court: "[T]he Board … requested that TriVascular explain why it would have been obvious to replace just the barbs of Samuels '851 with the circumferential ridges of Todd, in view of the Board's findings regarding the stated purposes of each prior art reference." (Id. at 20.) The court concluded that the Board's findings regarding "the lack of a sufficient motivation to combine and the lack of a reasonable expectation of success in combining the prior art are supported by substantial evidence." The court therefore correctly found that the Board did not err in concluding that TriVascular had failed to meet its heightened burden of demonstrating (after institution of the IPR) that the asserted claims are invalid as obvious.