Reissue Applications and Patents

Under certain circumstances after a patent has already issued, the patentee can withdraw the issued patent and subject it to a reissue process, which can result in a new patent the reissue patent. Reissue patents are identified by the prefix RE followed by the number of the patent (e.g., RE 39,424). It is not surprising that a reissue patent originates from a reissue application. The reissue application process occurs when a patent is withdrawn from issue by its patentees and submitted as an application to the patent office for further prosecution. In order to do so, the patentee must assert that the patent is  

One possibility for seeking a reissue patent includes the situation in which the patentees discover prior art that they were not aware of during the prosecution of the patent application, but that could affect the validity of one or more of their patent claims such that they might tike to narrow the claim(s) to avoid the prior art and thus provide them with the maximum patentable scope for their invention. 

a reissue application that seeks to broaden any of the claims (in any way) of the original issued patent can do so only if the reissue application is submitted within 2 years of the original patent s issuance. However, the reissue application needs to be only filed within the 2-year period from the original patent s issue date the actual broadened claims in the reissue application may be added after a period of greater than 2 years from the original patent s issue date, provided they are added as part of the reissue patent application that was filed within the 2-year period. 

Finally (and perhaps most important), under the doctrine of intervening rights (35 U.S.C. 252) relief is provided for defendants who did not infringe an original patent but do infringe the patent as reissued. Paragraph 2 of 35 U.S.C. 252 provides the following  

A reissued patent shall not abridge or affect the right of any person or that person s successors in business who, prior to the grant of a reissue, made, purchased, offered to sale, or used within the United States, or imported into the United States, anything patented by the reissued patent, to continue the use of, to offer to sale, or to sell to others 

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