How is the best mode requirement assessed in patent examinations?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

Assessing compliance with the best mode requirement during patent examination is a challenging task due to its subjective nature. The MPEP 2165.01 provides guidance on how examiners approach this assessment:

“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 discovery procedures in interference, litigation, or other inter partes proceedings.”

This means that:

• Examiners typically do not have access to information about the inventor’s subjective best mode.
• Rejections based on failure to disclose the best mode are rare during examination.
• Examiners generally presume that the best mode is disclosed unless there is evidence to the contrary.
• Issues with best mode compliance are more likely to arise in post-grant proceedings or litigation.

Despite these challenges, applicants are still required to disclose the best mode known to them at the time of filing, even if it’s difficult for examiners to verify compliance during the initial examination.