Negative claim limitations may be supported by the specification’s description of alternative features—even without articulating advantages or disadvantages of each feature—which can constitute a “reason to exclude” under the standard for supporting negative limitations articulated in Santarus. Here, for example, the specification’s distinction between different types of memory “chip select” signals was found to be sufficient to support a negative limitation excluding three particular types of signals. “We hold that Santarus did not create a heightened written description standard for negative claim limitations and that properly described, alternative features are sufficient to satisfy the written description standard of § 112, paragraph 1 for negative claim limitations.” This would be a good case to consult and cite in response to a rejection of a negative limitation for lack of written description support.
Background / Facts: The patent on appeal here from rejection at the PTO during inter partes reexamination proceedings is directed to improving the performance and/or capacity of computer system memory modules. During reexamination, the patentee added a negative claim limitation limiting the claimed “chip selects” (or control lines) to exclude three particular types of signals (CAS, RAS, and bank-address signals).
Issue(s): Whether the specification provides a “reason to exclude” CAS, RAS, or bank address signals that is sufficient to satisfy the written description requirement for negative limitations laid out in Santarus.
Holding(s): Yes. “When viewed in its proper context, Santarus simply reflects the fact that the specification need only satisfy the requirements of § 112, paragraph 1 as described in this court’s existing jurisprudence. … The ‘reason’ required by Santarus is provided, for instance, by properly describing alternative features of the patented invention.” In this case, “the parties agree that the disclosure in the [] patent distinguishes among the relevant signal types, but simply disagree about whether that distinction creates a ‘reason to exclude’ that satisfies the requirements of § 112, paragraph 1. … We hold that Santarus did not create a heightened written description standard for negative claim limitations and that properly described, alternative features are sufficient to satisfy the written description standard of § 112, paragraph 1 for negative claim limitations.”