During the prosecution of a patent application before the U.S. Patent and Trademark Office, claim amendments that introduce a negative limitation―the exclusion of a particular element or feature from the scope of the claims―may be dispositive in distinguishing the instant application from the prior art and advance the application toward allowance. However, the introduction of negative limitations may raise questions and issues as to whether the claims satisfy the written description requirement under 35 USC §112(a). Recently, the U.S. Court of Appeals for the Federal Circuit elaborated upon what satisfies the written description requirement with respect to the recitation of negative claim limitations.
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