Chapter §21.06 Reexamination Compared to Reissue

• Jurisdiction: United States

§21.06 Reexamination Compared to Reissue

The reexamination and reissue procedures differ in fundamental respects. Reexamination is narrower than reissue in the sense that reexamination cannot be used to correct defects other than anticipation and obviousness based exclusively on the content of the prior art references.²⁹⁷ Reexamination is broader than reissue, however, in the sense that anyone can request reexamination,²⁹⁸ while only the owner of the patent in question can seek to reissue it.²⁹⁹

The most important difference between the two procedures is likely the fact that, unlike reissue, reexamination cannot be used to broaden the claims of an issued patent.³⁰⁰ There is no broadening reexamination. For example, in Quantum Corp. v. Rodime, PLC,³⁰¹ the accused infringer brought a declaratory judgment action seeking a declaration that a previously reexamined patent, directed to a micro hard-disk drive system suitable for use in personal computers, was invalid and not infringed. The validity challenge was based on the facts that as originally issued, the claims of the patent recited a track density of "at least 600 concentric tracks per inch," but that during reexamination, the patentee amended the claims to recite "at least approximately 600 concentric tracks per inch," and the USPTO issued a reexamination certificate confirming the patentability of these amended claims. The accused infringer thus contended that the amendments made by the patentee during the reexamination amounted to an impermissible broadening of the claims, as prohibited by 35 U.S.C. §305.

The Federal Circuit in Quantum Corp. agreed, pointing to dictionary definitions of "at least" as meaning "as the minimum," and thus interpreted the original claim language as meaning "600 tpi on up." The addition of the approximately qualifier during reexamination eliminated the precise lower limit of the range, the court concluded, and therefore defined an open-ended range starting slightly below 600 tpi. This constituted an impermissible broadening of claim scope in reexamination. The Federal Circuit refused to rewrite the claims back to their original scope. Because the patentee had violated the terms of §305, the claims of the reexamined patent could not stand. The reexamined patent was therefore invalid.

Another important difference between reexamination and reissue concerns timing. Reexamination may be requested at any time during the life of a patent.³⁰² In contrast, when a reissue application...