United States: Disclosure Requirements for § 112, ¶6 Key to Level of Skill in the Art

The U.S. Court of Appeals for the Federal Circuit recently upheld a summary judgment of non-infringement based on a license defense involving an industry standard. The Court also wrestled with the issue of whether a specification that fails to disclose specific structure corresponding to a functional limitation satisfies the disclosure requirement. Intel Corp. v. VIA Technologies, Inc., Case Nos. 02-1212, -1213 (Fed. Cir. February 14, 2003).

The patent at issue (the `291 patent) relates to "Fast Write" technology, an optional protocol for what is known as the accelerated graphics port (AGP) interface specification developed by Intel. The `291 patent specification describes how AGP permits graphics devices to communicate with the core logic without using the slower, peripheral interface component (PCI) bus. Intel licenses the AGP protocol to interested parties on a reciprocal, royalty-free basis, as a way of setting the industry standard for certain computer-chip specifications. The license covers any patent claims that "must be infringed in order to comply with" the standards set out in the AGP specification. VIA acquired an AGP license and conceded that its products practiced several claims of the `291 patent, but asserted that its activities were covered by the AGP cross-license agreement. Intel sued, asserting VIA’s activities were outside the scope of the AGP license. VIA also cross-claimed for a declaratory judgment of invalidity of the `291 patent on the basis that the patent failed to disclose structure corresponding to the recited function in a "means-plus-function" claim element. The district court granted VIA’s summary judgment of non-infringement, but did not find Intel’s patent to be invalid.

The Federal Circuit upheld both rulings. The Federal Circuit found that the terms of the AGP license agreement were subject to more than one reasonable interpretation, i.e., that there was ambiguity in the agreement as to whether "Fast Write," an optional protocol, was covered by the license. The Federal Circuit held that "[w]hen a contract is ambiguous, the principle of contra proferentum … requires that the agreement be construed against the drafter who is solely responsible for its terms." Because Intel alone had drafted the non-negotiated license agreement, and the agreement was ambiguous as to whether it covered the "Fast Write" protocol, the Federal Circuit resolved the ambiguity against Intel.

The Federal Circuit also agreed with the district court that the claims of the `291 patent were not invalid for indefiniteness. VIA had argued that the claim at issue was indefinite because the `291 patent specification failed to disclose adequate structure corresponding to the function recited in a means-plus-function claim element. The district court rejected this contention, finding that "the core logic of a computer modified to perform Fast Write is the corresponding structure for the functions recited." VIA did not dispute this finding, but maintained that "a generic core logic is an inadequate disclosure of structure because no circuitry is disclosed to show the modification." The Federal Circuit posed the test as whether VIA had proven, by clear and convincing evidence, that the specification lacks adequate disclosure of structure, as it would be understood by one of skill in the art, to perform the recited function. Answering in the negative, the Federal Circuit held that the patent "is not indefinite merely because no specific circuitry is disclosed" to show how the core logic is modified to perform Fast Write reasoning that "[h]ow to modify the core logic to perform Fast Write on the circuitry level may … be properly left to the knowledge of those skilled in the art, and need not be identified in the patent."

The Federal Circuit, noted that the specification of the `291 patent included three diagrams, 35 signal charts and a detailed written description explaining the invention and a generic description of the core logic as adapted to practice Fast Write pursuant to the specification. Thus, the Court found sufficient corresponding structure notwithstanding the absence of circuitry.

Finally, the Federal Circuit rejected VIA’s argument that absent a disclosure of structure, i.e., circuitry, the scope of what constitutes corresponding disclosed structure plus equivalents is indefinite, making it impossible for competitors to design around the patent. The Federal Circuit held that even if there are multiple ways to implement the claimed function in circuitry, the claim was not invalid simply because the universe of such implementations is undefined. Rather, the Court noted that the "novelty of the invention" was in the signal protocol for implementing Fast Write, "not in unclaimed circuitry" for carrying out the specified protocol. Thus, one may design around the invention by using another signal protocol.

Practice Note: When drafting claims having a means-plus-function element, the written description should include "corresponding structure" for every m+f limitation and "clearly links" the corresponding structure to the recited function. Although details of structures that are generally known by those skilled in the art need not be included, if there is any doubt on the issue, prudence counsels inclusion of such structural details.