How common are best mode rejections in patent examination?

Best mode rejections are extremely rare in patent examination, particularly in ex parte prosecution. The MPEP 2165.03 explicitly states:

“It is extremely rare that a best mode rejection properly would be made in ex parte prosecution. The information that is necessary to form the basis for a rejection based on the failure to set forth the best mode is rarely accessible to the examiner, but is generally uncovered during inter partes proceedings.”

This rarity is due to the difficulty in obtaining evidence that the inventor knew of a better mode at the time of filing but failed to disclose it. Such information is typically not available to examiners during standard patent prosecution.

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Topics: MPEP 2100 - Patentability, MPEP 2165.03 - Requirements For Rejection For Lack Of Best Mode, Patent Law, Patent Procedure
Tags: Best Mode Rejection, Ex Parte Prosecution, Inter Partes Proceedings, patent examination