Is there a diligence requirement for filing narrowing reissue applications?

While the MPEP 1403 generally does not impose a diligence requirement for filing reissue applications, especially within the first two years, recent court decisions have considered diligence in certain cases. The MPEP states:

“While examiners should not make rejections based on lack of diligence (which does not include rejections under 35 U.S.C. 251 for a broadening reissue that is impermissibly filed outside of the two year time period set in 35 U.S.C. 251), courts have looked to see if a reissue applicant was diligent in correcting the error(s) in the patent.”

The MPEP cites the case of In re Rosuvastatin Calcium Patent Litigation, where the court considered the diligence of the patentee in filing a narrowing reissue application. While the majority found the applicant diligent, the dissenting opinion raised concerns about a long delay in filing the reissue. This suggests that while there’s no strict diligence requirement, courts may consider it in certain circumstances.

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Tags: Court Decisions, diligence requirement, narrowing reissue, Patent correction