Patent Claim Limitations

Patent claim limitations that are “negative”—that is, claim limitations specifying the absence of a particular element from the patent claim—can pose a dilemma in the written description context. How much of the specification should be devoted to something that is not supposed to be part of the claim? The answer may be none at all according to a recent Federal Circuit decision, Novartis Pharmaceuticals v. Accord Healthcare Inc. The key, according to the decision, is that the specification should not describe the negative limitation in a manner inconsistent with how it is used in the claim.