Errors in an issued patent can be corrected in one of four ways: (1) filing a request that the USPTO issue a certificate of correction, (2) filing a disclaimer of one or more claims (3) filing a request for reexamination of the patent, and (4) filing a reissue patent application. If a patentee wishes to broaden the scope of one or more claims in an issued patent, the reissue application must be filed within 2 years of the issue date of the patent.
Law - Reissue Application Broadening Claims