CAFC Reminds the Patent Office to Play Fair When Issuing New Grounds of Rejection and Evaluating Objective Evidence of Non-Obviousness

Cindy Chen | October 3, 2013

Rambus Inc. v. Rea

September 24, 2013

Panel of Moore, Linn, and O’Malley, Opinion by Moore


The Court of Appeals for the Federal Circuit in Rambus Inc. v. Rea reminds Examiners and the Board of Patent Appeals and Interferences (now the Patent Trial and Appeal Board) that procedural checks remain in place for issuing new grounds of rejection. Examiners and the Board cannot bury a new ground of rejection in a decision, without ensuring that a patent applicant has had a fair opportunity to respond to the rejection. Indeed, whether the applicant has had a fair opportunity to react to the thrust of the rejection is reiterated as the ultimate determination of whether a rejection is considered “new”.

In line with the Federal Circuit’s recent decision in Leo Pharmaceutical Products v. Rea, Rambus is also a reminder that objective evidence of non-obviousness must be given due consideration and weight. Examiners and the Board cannot undercut an applicant’s objective evidence of non-obviousness through an overly stringent interpretation of the nexus and “commensurate in scope” requirements.


Rambus is the owner of U.S. Patent No. 6,260,097 (the ‘097 patent). The ‘097 patent was challenged in an inter partes reexamination, which saw the invalidation of various claims for anticipation and obviousness. Rambus’s appeal to the Board of Patent Appeals & Interference was unavailing, and the invalidation was affirmed. From that decision Rambus appealed to the Federal Circuit.

The ‘097 patent relates to an integrated memory circuit known as synchronous dynamic random-access memory (DRAM), for high-speed transfers of large blocks of data to and from a single memory device. A synchronous DRAM uses a clock signal to synchronize the timing of data transfers. Claim 1 is representative, and is reproduced in part below:

1.         A method of controlling a synchronous memory device, wherein the memory device includes a plurality of memory cells, the method of controlling the memory device comprises:

issuing a write request to the memory device . . .

providing a first portion of data to the memory device synchronously with respect to a rising edge transition of an external clock signal; and

providing a second portion of data to the memory device synchronously with respect to a falling edge transition of the external clock signal

(emphasis added).

A key feature of Rambus’s memory system is its “clocking scheme”. A conventional clocked circuit performs one transfer of data per full cycle of a clock signal. Only the rising edge of a clock signal is used to transfer data. Meanwhile, Rambus’s memory system utilizes what is known as the “double data rate” functionality. As the name implies, such functionality doubles the rate at which data is transferred, by separating a large block of data into chunks, and transmitting chunks of data on both the rising and falling edges of the clock signal. The “double data rate” functionality increases the bandwidth of the DRAM system.

Two prior art references are of particular relevance. The Intel iAPX specification describes a memory system that could transfer data on either the rising or the falling edge of a clock signal, but since the system requires a full cycle for each data transfer, the system cannot use both edges. The memory system of Inagaki (Japanese Patent Application No. 56-88987) performs one transfer during each half-cycle of a clock signal. The half-cycles are defined by the rising and the falling edges of the clock signal.

During reexamination, the Examiner determined that the reexamined claims would have been obvious in view of the iAPX specification in combination with Inagaki. On appeal, the Board agreed with Rambus that the Examiner’s rationale for combining the cited prior art was based on a mischaracterization of the teachings of the iAPX specification.

However, recognizing the Examiner’s mischaracterization, the Board instead offered alternative modifications that one skilled in the art could have made to the iAPX system, based on Inagaki’s teachings, to arrive at Rambus’s claimed invention. The Board determined that “skilled artisans easily could have modified the iAPX system in view of Inagaki’s clocking scheme by dropping, instead of replacing, many functions”. Alternatively, one skilled in the art would have “recognized that the iAPX system could have been modified to include the external slower Inagaki clock as a trigger for the faster [clocks in iAPX]—thereby retaining all existing APX functions.”

On appeal to the Board, Rambus also presented objective evidence of non-obviousness, including long-felt need, commercial success, and industry praise. The Board dismissed the proffered evidence for various reasons. The Board found that Rambus’s evidence lacked nexus to the claims and was not commensurate in scope with the scope of the claims, because the evidence touched upon unclaimed features or features that were disclosed in the prior art. Further as to Rambus’s licensing activities as evidence of commercial success, the Board found that “competitors have many reasons for taking licenses which are not necessarily related to unobviousness (i.e., litigation costs, etc.).”

The Federal Circuit opinion was interesting for its treatment of the Board’s determination of obviousness. More particularly, the Federal Circuit found multiple errors with the Board’s determination. For starters, the Federal Circuit reiterated the proper burden of proof in a reexamination proceeding. Namely, “a preponderance of the evidence must show nonpatentability before the PTO may reject the claims of a patent application.” The Board in this case misplaced the burden of proof on Rambus when it asserted that “Rambus had not demonstrated that skilled artisans  . . . would not have been able to arrive at the broadly claimed invention”. The burden always remains with the Patent Office to present evidence of invalidity.

Next, the Federal Circuit faulted the Board for supplying its own rationale as to how the cited prior art could be combined. This rationale amounted to a new ground of rejection. The Federal Circuit has held that the thrust of the Board’s rejection changes when the Board finds facts not found by the Examiner regarding the differences between the prior art and the claimed invention, and when those facts are the principal evidence upon which the Board’s rejection rests. In re Adler, 723 F.3d 1322, 1327 (Fed. Cir. 2013); In re Leithem, 661 F.3d 1316, 1320 (Fed. Cir. 2011). The ultimate criterion of whether the Board’s rejection should be considered “new” is whether an applicant has had “a fair opportunity to react to the thrust of the rejection”. In re Adler, 723 F.3d at 1327; In re Kronig, 539 F.2d 1300, 1302–03 (CCPA 1976).

The “fair opportunity” speaks to the applicant’s due process rights at the Patent Office. To that end, the Board “may not rely on new facts and rationales not previously raised to the applicant by the Examiner”. As the reviewer of the Examiner’s decision during prosecution, the Board is certainly permitted to elaborate on the Examiner’s findings in more detail, so long as the applicant has an adequate opportunity to respond to the Board’s findings.

In this case, the Federal Circuit found that the Board’s proposed alternative combinations of iAPX and Inagaki went beyond a merely more‑detailed elaboration of the Examiner’s findings, and in fact constituted completely new findings. The Federal Circuit reminded the Board that there are procedures in place for issuing new grounds of rejections, and that such procedures may not be circumvented. The Federal Circuit effectively discounted the Board’s rationale for combining the cited art, without addressing the merit of the rationale.

Finally, the Federal Circuit found that the Board erred in its treatment of Rambus’s objective evidence of nonobviousness. The Federal Circuit easily dismissed the Board’s assertions regarding Rambus’s licensing activities as being entirely unsupported by evidence in the record. Rather, the Federal Circuit seemed primarily troubled by the Board’s overly restrictive interpretation of the nexus and “commensurate in scope” requirements. The Board seemed to have nitpicked at Rambus’s evidence of secondary considerations, finding reasons to whittle the mountain of evidence to a molehill.

For one thing, objective evidence of nonobviousness need only be “reasonably commensurate with the scope of the claims”. There is no requirement that the evidence must correspond to every potential embodiment of the claimed invention. For another, Rambus’s objective evidence of nonobviousness did not “exclusively relate” to unclaimed features or features already known in the prior art. At least some of the evidence pertained to the claimed features or to the overall architecture of Rambus’s memory device. Emphasizing that the obviousness inquiry is with respect to “the claimed invention as a whole”, the Federal Circuit instructed that “the Board should be careful to parse the evidence that relates only to the prior art functionality and the evidence that touted Rambus’s patented design as a whole”.


In evaluating objective evidence of non-obviousness, the Examiner and the Board often impose an overly stringent test for the nexus and “commensurate in scope” requirements, thus steeply discounting the probative weight of the evidence. When presenting objective evidence of non-obviousness, it could therefore be helpful to first remind the Examiner and the Board of the proper standards before laying out and explaining the evidence.

Portions of the Federal Circuit decision in Rambus concerning new grounds of rejection seem straightforward and grounded in good policy. Requiring that the Board designate new rejections as “new” gives procedural protections to the patent applicant. For example, the patent applicant would then be free to reopen prosecution or to request rehearing. However, in Rambus, the Board’s new ground of rejection probably would not have been dispositive of the case, without the Examiner’s initial error of mischaracterizing one of the cited references. The Federal Circuit is unlikely to remand a case merely for housekeeping reasons, that is, to clarify the record. Rambus is thus not an invitation to focus on “new grounds of rejection” arguments, for the possibility of reopening prosecution or requesting rehearing.

Full Opinion




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