How can I prove that a joint inventor cannot be found or refuses to sign the application?

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.

To prove that a joint inventor cannot be found or refuses to sign the patent application, you must provide evidence of your diligent efforts. According to MPEP 409.03(a):

“The application must be accompanied by proof that the nonsigning inventor (1) cannot be found or reached after diligent effort or (2) refuses to execute the application papers.”

For specific guidance on what constitutes acceptable proof, refer to MPEP 409.03(d). This may include documented attempts to contact the inventor, returned mail, or written statements from the unavailable inventor indicating their refusal to sign.