For the very first time, the Court of Appeals for the Federal Circuit (CAFC) has reversed a decision by the Patent Trial and Appeal Board (PTAB) in an AIA trial. In inter partes review numbers 2012-00026 and 2013-001091, the PTAB held that only one claim, claim 24, of U.S. Patent 6,757,717 owned by Proxyconn, Inc. was patentable. The claims of the patent are directed to increasing the speed of data access in a packet-switched network, through use of “digital digests” that serve as digital fingerprints for the corresponding documents.

In deciding that only claim 24 was patentable, the PTAB construed the claimed “gateway… between at least two other computers” to be a gateway between any computers connected to a network, including the claimed “caching computer.” Based on this construction, the PTAB held that claims 6, 7, and 9 were anticipated by the prior art.

However, the CAFC noted that:

Not only are the “two other computers” recited independently from, and in addition to, the gateway and caching computers, the word “other” denotes a further level of distinction between those two computers and the specific gateway and caching computers recited separately in the claim. …

Other than in claim 6 itself, the phrase “two other computers” is used three times in the specification, each time as part of the embodiment containing the gateway and caching computer intermediaries.

Microsoft Corporation v. Proxyconn Inc., Case No. 2014-1542, -1543, Slip Op. at 9. (Fed. Cir. June 16, 2015)

In view of the above, the CAFC held that the PTAB’s construction of “gateway… between at least two other computers” was unreasonably broad and thus improper under the “broadest reasonable construction” standard that is generally applied in PTAB proceedings.

Further, the PTAB construed the terms “sender/computer” and “receiver/computer” of claims 1, 10, and 22 to respectively mean a computer that sends and a computer that receives. Under this construction, the PTAB held that claims 1, 3, 10, 22, and 23 were anticipated by the prior art because the sender/computer and the receiver/computer could include the claimed “intermediary gateway” and the claimed “caching computer.”

Again, the CAFC looked at the claim as a whole and the use of the terms in the specification.

The Board erred in concluding that the terms “sender/computer” and “receiver/computer” were broad enough to include the intermediary gateway and caching computers for similar reasons as explained above. The language of the specification consistently refers to the sender/ computer, receiver/computer, gateway, and caching computers as separate and independent components of an overall system. The figures of the ’717 patent separately identify and number each component of the system. And nowhere does the ’717 patent indicate that the gateway and caching computer are the same as, or can be subsumed within, the sender/computer and receiver/computer.

Id., at p. 11.

The CAFC vacated the PTAB’s findings of unpatentability of claims 1, 3, 6, 7, 9, 10, 22, and 23 because the determinations of unpatentability were based on unreasonably broad claim constructions. The CAFC previously affirmed that the broadest reasonable interpretation standard is the proper standard to be applied by the PTAB2. However, this case makes it clear that the “reasonable” qualifier requires that terms be construed in the context of the claim and the specification, not in a vacuum.

Those challenging patents through post-grant proceedings in the Patent Office should propose claim constructions that take into account how the terms are used in the specification. On the other hand, Patent owners may be able to demonstrate patentability based on the use of the claim terms in the specification and in the claims as a whole. Finally, patent drafters should give great thought to construction of key claim terms, should use them consistently, and might want to consider proffering specific definitions in the patent specification.


  1. The two reviews were consolidated into a single proceeding.
  2. Except for patents that have expired. See, In re Cuozzo Speed Technologies, LLC, Case No. 2014-1301 (Fed. Cir. Feb. 4, 2015)