Addressing the rules of claim construction pertaining to preambles and preferred embodiments, the U.S. Court of Appeals for the Federal Circuit vacated the district court's summary judgment of non-infringement. Symantec Corp. v. Computer Assoc. Int'l, Inc. et al, Case Nos. 07-1201, -1239 (Fed. Cir., April 11, 2008) (Dyk, J.).

Symantec Corporation appealed from the district court's summary judgment that Computer Associates Int'l, Inc. did not infringe U.S. Patent No. 5,319,776 (the '776 patent). Symantec argued the district court erred in its claim construction on two grounds: reading a term from the preamble as a claim limitation and limiting the scope of a claim term to the preferred embodiment.

On appeal, the Federal Circuit noted that the "the purpose of a claim preamble is to give context for what is being described in the body of the claim." According to the Court, preamble language is assumed to be "duplicative of the language found in the body of the claims" unless the claims, specification or prosecution history indicate otherwise. Here, the Court determined the prosecution history showed the terms "as it is being transferred" and "prior to storage" were added concurrently to overcome the same prior art. This did not constitute "clear reliance" on the preamble to distinguish from the prior art. Furthermore, nothing in the claim or specification suggested the terms have different meanings. Accordingly, the Court concluded the preamble term "as it is being transferred" simply meant "prior to storage" and did not impose a separate claim limitation.

The Court also agreed with Symantec that the district court improperly limited the claim term "computer system" to cover only the preferred embodiment. Citing its decision in Phillips, the Court noted "the claims 'must be read in view of the specification, of which they are a part.'" The Court found the specification did not expressly or specially define the term "computer" or "computer system," thus the words should be given their "ordinary and customary meaning." The Court relied on the Dictionary of Computing to determine that the ordinary meaning of the words, as understood by a person of ordinary skill in the art at the time of invention, was not limited to a single, stand-alone computer. In view of the correct construction of "computer system," the Court also determined the district court erred in construing the term "destination storage medium" to encompass only a storage system residing within a single, stand-alone computer, i.e., a hard drive. "Destination storage medium" could properly include peripheral devices in addition to hard drives, a scope consistent with the broad construction of "storage medium" determined in a prior Federal Circuit case involving the patent-in-suit.

Due to these errors in claim construction, the Court vacated and remanded the district court's decision on non-infringement and invalidity. In the decision, the Court also addressed laches, inequitable conduct and inventorship, affirming the district court's decision on each of these issues.

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