Preamble not limiting when duplicative of claim limitations and not added to overcome rejection

April 16, 2008
Post by Blog Staff

In a recent decision, the Federal Circuit held that a district court erred in its construction of several claim terms in a patent, and as a result, vacated the district court's summary judgment of noninfringement and no invalidity. The court affirmed the district court's decisions regarding several other issues, including laches, inequitable conduct, and inventorship.

One of the claim terms at issue was in the preamble of the claims. The court noted that "if [the preamble term] is reasonably susceptible to being construed to be merely duplicative of the limitations in the body of the claim (and was not clearly added to overcome a rejection), we do not construe it to be a separate limitation."

Symantec is the assignee of U.S. Patent No. 5,319,776, which is directed to "a method of scanning for and detecting computer viruses embedded in data files that are downloaded or copied from a remote server (e.g., via the internet) onto a computer." The virus scan operates prior to the downloaded or copied files being accessible to the operating system of the computer, thus any viruses detected are prevented from infecting the computer. Symantec brought suit against Computer Associates, arguing that some of its antivirus programs infringed the '776 patent, and that other programs resulted in induced infringement.

The parties disputed the scope of several terms before the district court. The court held the claim term "a method of screening the data as it is being transferred," contained in the preamble of the claims, was limiting and construed the term to mean "a method of screening the data while it is being moved or copied and before the data is stored to the computer storage medium." The district court construed "computer" and "computer system" as limited to a "single personal computer or workstation." The district court construed the term "destination storage medium" as "a computer storage medium that is the target of the transfer of data as a result of the causing step." This construction, in conjunction with the district court's construction of the terms "computer" and "computer system," limited the term "destination storage medium" to a "storage system residing within a stand-alone computer." Based on these constructions, the district court granted summary judgment of noninfringement and no invalidity. Both parties appealed.The Federal Circuit disagreed with the district court's constructions. Turning first to whether the disputed preamble term was a limitation, the court noted that a preamble is generally construed as a limitation "if it recites essential structure or steps, or if it is 'necessary to give life, meaning, and vitality' to the claim," but is generally not limiting "where a patentee defines a structurally complete invention in the claim body and uses the preamble only to state a purpose or intended use for the invention." The court added that "if it is reasonably susceptible to being construed to be merely duplicative of the limitations in the body of the claim (and was not clearly added to overcome a rejection), we do not construe it to be a separate limitation." In this case, the court held the preamble was not limiting. The language was added at the same time as another limitation in order to distinguish the prior art, but did not have its own independent significance. As such, there was no "clear reliance on the preamble during prosecution to distinguish the claimed invention from the prior art." Further, simply using different language in the preamble as compared to the body of the claim "does not suggest that the preamble imposes a limitation." Instead, the assumption is that the preamble is duplicative, and therefore not a limitation. Based on this (along with the court's construction of "storage" in a previous appeal), the preamble was not limiting. The Federal Circuit next analyzed the construction of the terms "computer" and "computer system." The court noted that nothing in the specification limited the terms to a single computer or workstation or adopted a special definition for these terms. They should therefore be construed according to their ordinary meaning. Citing the 1986 edition of Dictionary of Computing, the court stated that "it is clear that the ordinary meaning of the terms 'computer' or 'computer system' as understood by a person of ordinary skill in the art at the time of the invention is not limited to a single computer or workstation." Turning to the final limitation, "destination storage medium," the court held that given its construction of "computer" and "computer system," this term "destination storage medium" should not be limited to a hard drive, and should include "peripheral devices, such as floppy drives and thumb drives." Based on these revised constructions, the court vacated the district court's summary judgment of noninfringement and no invalidity and remanded for reconsideration.The Federal Circuit next addressed the district court's finding of noninfringement of Computer Associates' EAV products based on the district court's finding that Computer Associates did not induce infringement of the '776 patent. The Federal Circuit noted that inducement "requires more than just intent to cause the acts that produce direct infringement. . . . [T]he inducer must have an affirmative intent to cause direct infringement." The Federal Circuit also noted that Computer Associates encouraged customers to directly infringe by using EAV products in conjunction with a downloading program. Thus, even though Symantec had not produced any evidence that "any particular customer has directly infringed the '776 patent," the Federal Circuit held that there was a genuine issue of material fact regarding the issue of inducement.The Federal Circuit affirmed the district court's summary judgment to Symantec regarding Computer Associates laches defense and inequitable conduct claim, as well as the district court's conclusion that no genuine issue of material fact existed regarding inventorship.To read the full decision in Symantec Corp. v. Computer Assocs. Int'l, Inc., click here.

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