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Wang Lab., Inc. v. Am. Online, Inc., No. 98-1363, 197 F.3d 1377, 1999 U.S. App. LEXIS 32841 (Fed. Cir., Dec. 17, 1999).




Whether a patent's claims are limited to the specific technology by which the invention functions.


Generally, yes. Unless the specification description sufficiently satisfies 35 U.S.C. 112 for additional technologies, only the specifically enabled technology and direct functional equivalents are covered by the claims.


Wang Laboratories, Inc. ("Wang") owns U.S. Patent No. 4,751,669 (the '669 patent) directed to an online information retrieval system. The invention allows users to interface with existing computer databases to search, retrieve, and store textual and graphic information via an interactive two-way communication over a telephone network (i.e., the Internet). The specification describes a character-based system used to process and display frames of information in which the screen display is divided into a grid. Characters, such as letters or numbers, are placed on each cell of the grid. At the time of invention, bit-mapped technology, in which images are encoded with reference to individual pixels of the display monitor, was also known and limited interchangeability existed between the two protocols.

Wang filed suit against America Online, Inc. and Netscape Communications, Corp. ("AOL and Netscape") for literal infringement and infringement under the doctrine of equivalents of the '669 patent. Both AOL and Netscape employ bit-mapped protocol systems. Wang asserted that AOL's "favorite places" and Netscape's "bookmark" features each infringe the '669 patent, which has a keyword feature that allows the user to assign a name to a particular frame for ease in later retrieval.

The district court construed all of the claims at issue as limited to character-based protocols based on the patent's definition of the term "frame" as a "page of information ...encoded in a character-based protocol..." Using this construction, the district court found that the claims did not read on AOL and Netscape's bit-mapped protocols for lack of sufficient description under 112 or qualify for infringement under the doctrine of equivalents; thus, the district court granted summary judgment to AOL and Netscape on both issues. Wang appealed.

Wang argued that the claim language did not restrict the invention solely to character-based protocols because use of means-plus-function claims and the term "preferred embodiment" to describe the invention impliedly covers other, functionally equivalent technologies. Additionally, Wang asserted that a claim is not invalid simply because it embraces subject matter that is not specifically illustrated in the application. AOL and Netscape argued that the invention was solely directed to the character-based technology and did not either reference or provide sufficient description to enable the invention using bit-mapped technology, although the technology existed to convert between the two.

The Court noted that claim validity is a separate issue and did not apply to construction of the claims for the technology disclosed. The Court held that in order to be covered by the claims, the subject matter and the means by which the invention functions must be sufficiently described in the patent's specification to meet the requirements of 112. The Court also held that use of means plus function claims or of the term "preferred embodiment" does not inherently broaden the claims beyond their support in the specification.

The Federal Circuit construed the claims de novo, and found that the district court did not clearly err in finding that the '669 patent functioned solely through a character-based protocol. The Court found support in the patent prosecution history in which Wang distinguished prior art from its invention as "referring to bit-mapped and not character-based technology." Additionally, expert testimony indicated that Wang scientists were unable to construct an embodiment of the invention using bit-mapped technology and thus could not have sufficiently described the invention to adequately enable it.

With respect to the issue of equivalence, the Court found that the extensive differences in the operation, structure, and capabilities of the two systems precluded them from being the types of functional equivalents covered under the doctrine. Thus, the Federal Circuit affirmed the respective summary judgments for AOL and Netscape.


Prepared by the liibulletin-patent Editorial Board.

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