## Facts

- Inventors filed a patent application with claims to (1) a limonin quantitative assay method and (2) separate organic and protein compound inventions.
- The examiner issued a restriction requirement, finding three independent and distinct inventions, and required election among the groups of claims.
- The inventors elected to prosecute only the assay method claims and did not contest restriction or file a divisional application for the non-elected compound claims.
- The method claims issued as a patent covering a competitive binding assay using limonin-specific antibodies and a labeled limonin derivative.
- The inventors later filed a reissue application under 35 U.S.C. § 251, asserting the patent was partly inoperative because it claimed less than they had a right to claim due to error without deceptive intent.
- The reissue sought, through new claims, coverage directed to compound subject matter corresponding to the originally non-elected claims.
- The examiner rejected the reissue claims as improper under § 251, and the Board of Appeals affirmed, finding no evidence the inventors originally intended to claim those compound inventions in the issued patent.

## Issues

1. Whether reissue claims directed to compound inventions are proper under 35 U.S.C. § 251 when the applicant previously elected different claims after restriction and did not file a divisional.
2. Whether the record showed that the omitted compound subject matter was part of the same invention the patentee originally intended to claim, such that its omission was a correctable “error” under § 251.

## Decision

- The Federal Circuit affirmed the Board’s rejection of the reissue claims.
- The court held the inventors failed to establish that, at the time of the original prosecution, they intended the compound inventions to be claimed in the patent that issued.
- The court concluded reissue could not be used to obtain claims to separate, non-elected inventions effectively abandoned after restriction.

## Legal Principles

- Reissue under 35 U.S.C. § 251 is available to correct an issued patent that is partly inoperative or invalid because the patentee claimed more or less than entitled to claim, due to error without deceptive intent.
- Reissue may not be used to introduce a new and independent invention or to recapture distinct subject matter not intended to be claimed in the original patent.
- The patentee bears the burden to show (i) an error correctable by reissue, and (ii) that the reissue claims are directed to the same invention originally intended to be claimed in the patent that issued.
- Acquiescence in a restriction requirement and failure to file a divisional for non-elected inventions generally weighs against treating later efforts to claim those inventions as a § 251 “error.”

## Conclusion

The Federal Circuit held that reissue is limited to correcting errors in the scope of the invention the patentee originally intended to claim in the issued patent and cannot be used to add claims to distinct, non-elected inventions that were not pursued through a divisional after restriction.


In re Weiler, 790 F.2d 1576 (Fed. Cir. 1986)