Challenged Claims Survive Inter Partes Review Unchanged Twice

March 14, 2014

Shakelford Pic

Two recent Final Written Decisions from inter partes review proceedings offer patent owners a rare positive news – the survival of one or more of the challenged claims in its entirety.  Prior to these opinions, a Final Written Decision in an inter partes review or post-grant review always resulted in altering the challenged claim(s) in some respect.  Although the Board in each decision took different routes to reach their conclusions, the analyses in both turned on extrinsic evidence.  These decisions emphasize the importance of supporting arguments on claim construction and patentability with evidence outside the four corners of the challenged patent.  These two decisions are Microsoft Corp. v. Proxyconn, Inc. IPR 2012-00026 and 2013-00109 and Synopsis, Inc. v. Mentor Graphics Corp., IPR2012-00042.

In Microsoft Corp. v. Proxyconn, Inc., Microsoft filed two petitions for inter partes review of U.S. Pat. No. 6,757,717.  Both Petitions were granted, and the trials for each were subsequently joined.  Claims 1, 6, 10, 11 and 22 are the independent claims among the challenged claims of the ‘717 patent.  Claims 1, 6 and 10 are directed to systems, and claims 11 and 22 are directed to methods.  The Board found all the challenged claims invalid, except for method claim 24.

The ‘717 patent describes a system for data access that reduces transmission of redundant data.  The system comprises a sender and a receiver, wherein the sender and receiver communicate through a network to identify and prevent the transfer of redundant data.  As depicted in Fig. 5, a sender transmits a digital digest that is representative of data to be used by the receiver. The receiver checks its cache for the data, and if it does not have the data, a negative signal is sent to the sender, which then transmits the data.  If the receiver has the data, a positive signal is sent, the redundant data is not sent, and the receiver uses the data immediately.


Claim 24 recites a method for increased data access and depends from claim 22, which recites:


22:  A method for increased data access performed by a receiver/computer in a packet-switched network, said receiver/computer including an operating unit, a first memory, a permanent storage memory, a processor and a network cache memory, said method comprising the steps of:

receiving a message containing a digital digest from said network;

searching for data with the same digital digest in said network cache memory,

if data having the same digital digest as the digital digest received is not uncovered, forming a negative indication signal and transmitting it back through said network; and

creating a digital digest for data received from said network cache memory.


Claim 24 further specifies that a plurality of digital digests for different data objects is received in the same message, and an indication signal is generated separately for each of said data objects.

The patentability of claim 24 turned on the Board’s construction of “searching” in the limitation “searching for data with the same digital digest.”  Proxyconn argued that “searching” requires the capability to identify particular data from among a set of data.  Microsoft, on the other hand, argued that the ‘717 patent equates “search” with “check for” because the only search method described involved comparing two digest values for a match.  That is, “searching” meant comparing a digital digest from a sender with an existing digital digest at the receiver.

The Board found that the specification never expressly defined “search.”  In this absence, the Board turned to a dictionary definition of the limitation.  The Board found that “search” involved analyzing a set of items to identify one particular item from among a set of items.  The Board held that the limitation required an ability to identify a particular data object with the same digital digest from a set of potentially many data objects stored in the network cache memory, not merely comparison of digital digests.

Based on this interpretation, the Board found that the prior art references did not disclose “searching” as in claim 24, but rather merely disclosed comparing a received digital digest with an existing digital digest.  Despite the disclosure in the ‘717 patent specification of methods for carrying out the claimed invention, the Board relied on extrinsic evidence to determine the understanding of a person skilled in the art.

In Synopsys, Inc. v. Mentor Graphics Corp., Synopsys filed a petition for inter partes review of claims 1-15 and 20-33 of U.S. Patent No. 6,240,376.  The Board instituted trial for claims 1-9, 11, 28 and 29 on the sole ground of anticipation by U.S. Patent No. 6,132,109 (“Gregory”).  The Board held that claims 5, 8 and 9 were anticipated, but found that Synopsys had not met its burden to show anticipation of claims 1-4, 6, 7, 11, 28 and 29.

The ‘376 patent relates to the fields of simulation and prototyping of integrated circuits.  Integrated circuit design begins with a description of the behavior desired in a hardware description language (HDL), such as Register Transfer Language (RTL).  RTL source code can be simulated using software, which offer robust debugging functionality.  However, software RTL simulators are slow compared with hardware emulation.  Alternatively, synthesis tools can be used to generate a “gate-level netlist,” which can then be converted to a format suitable for programming a hardware emulator.  However, during synthesis of a gate-level netlist, high-level information from the RTL source code is lost, such as debugging functionality.

The ‘376 patent describes a method of synthesizing RTL source code in a manner that gate-level simulation does not lose debugging functionality. As depicted in Fig. 2, this method involves (1) generating instrumentation logic within the RTL source code; (2) generating a gate-level netlist from the RTL source code; and (3) during simulation using the gate-level netlist, evaluating the instrumentation logic to enable RTL debugging.

Gregory, the asserted prior art, describes a method of marking synthesis source code in places that a designer wants to be able to debug by marking the source code with a particular text phrase, such as “probe.”  Further, Gregory describes a translation process that interjects information into the netlist when it encounters a probe statement.

In considering patentability of the claims, the Board relied heavily on the testimony of Mentor Graphic’s expert.  Regarding claims 1-4, 28 and 29, the Board’s analysis turned on whether Gregory disclosed “an instrumentation signal indicative of an execution status of the at least one statement.”  Synopsys pointed to the disclosure in Gregory of an instrumentation signal tempout, as teaching this limitation.  However, Mentor Graphics’s Expert testified that a person skilled in the art would not consider the “tempout” as indicative of an execution status of the HDL statement.  The Board found Mentor Graphic’s Expert convincing and stated that Synopsys “does not point to any expert testimony to support [their] statements,” and their “unsupported argument to the contrary is not persuasive.”

The Board took a similar position with respect to claims 6 and 7, basing their finding of validity on testimony from Mentor Graphics’s Expert.  However, the Board did not side with Mentor Graphics for all of the challenged claims.  The Board found that Gregory anticipated claims 5, 8 and 9 and characterized Mentor Graphic’s arguments as “without detailed explanation.”  The lack of evidence in support of patentability for claims 5, 8 and 9 appears to have dictated a different result for these claims.

The Board also found that claim 11 was not anticipated by Gregory.  Synopsys stated in its Petition that Gregory anticipates claims 1-9, 11-14, 24-25 and 28-33.  However, Synopsys did not apply the disclosure of Gregory to claim 11 or present any evidence of anticipation.  The Board held that Synopsys’s statement was not evidence of anticipation.  Accordingly, the Board found that Synopsys had not met its burden to show invalidity of this claim.

The results in Microsoft and Synopsys emphasize the importance of evidentiary support in defining the knowledge of a person having ordinary skill in the art.  In Microsoft, despite exemplary disclosure in the specification, the Board relied on a dictionary definition to ascertain how a person skilled in the art would interpret “searching.”  Synopsys cautioned against asserting or challenging patentability without evidentiary support, wherein the Board repeatedly noted that their decision was heavily influenced by objective evidence and expert testimony.  The PTAB Trial Practice Guide states that, with respect to petitions and motions, “[t]he Board expects that most petitions and motions will rely upon affidavits of experts,” but that “[o]pinions expressed without disclosing the underlying facts or data may be given little or no weight.”  (Fed. Reg., Vol. 77, No. 157, pg. 48763).  Clearly these considerations apply to patent owner’s arguments as well.


Grant Shackleford


Mr. Shackelford is an associate in the chemical patent and biotechnology / pharmaceutical practice groups, where he maintains an active patent prosecution and litigation practice.

Prior to joining Sughrue Mion, Mr. Shackelford served as Intellectual Property Fellow at Illinois Institute of Technology Chicago-Kent College of Law, where he taught IP courses for LL.M. and J.D. students and conducted research into patent claim construction. During law school, Mr. Shackelford worked as a patent prosecution law clerk at the U.S. Department of Energy, evaluating invention disclosures, responding to Office Actions, and drafting patent applications. Prior to law school, Mr. Shackelford worked at the Midwest Center for Structural Genomics as an Associate Research Scientist, where he conducted and helped develop techniques for high-throughput cloning, expression, and crystallization of target proteins.

Mr. Shackelford earned his J.D. from the IIT Chicago-Kent College of Law, where he was a member of the Moot Court Honor Society and Law Review. He received his B.S. in Biochemistry from the University of Missouri-Columbia and M.S. in Chemistry and Chemical Biology from the University of California, San Francisco. As an undergraduate and graduate research scientist, Mr. Shackelford focused his research in the area of protein chemistry, studying protein superfamilies to identify mechanisms of enzymatic function and routes through which enzymes develop new functionality.

Admitted in Illinois only. Not a member of the DC Bar. Practice limited to certain matters before ‎federal agencies and courts. ‎