In the U.S. invention patent process, if the inventor loses contact, to what extent does the standard of evidence of reasonable efforts usually need to be met in practice?

The USPTO does not have a hard quantitative standard for reasonable efforts, but there are practice standards that can be followed. The USPTO describes reasonable efforts in MPEP § 602.10(c) as follows:

• Applicant must demonstrate that they have exercised reasonable diligence in attempting to contact the inventor to obtain the required oath or declaration.

In other words, reasonable efforts = reasonable diligent efforts, which does not require exhausting all possibilities, but cannot be just a formality.

Suggested steps to take in practice ( the more the better)

This is usually stated in the statement

• Substitute Statement often needs to be written: Despite reasonable efforts, the undersigned was unable to obtain a signed declaration from the inventor. Such efforts included multiple phone calls to the inventor's last known phone number, multiple emails to the inventor's last known email address, certified mail to the inventor's last known address (which was returned undelivered), and attempted contact through professional networks.

Examiner's review focus

• Tried multiple contact methods instead of just one
• Try to do it over a reasonable period of time, not just one short attempt
• Documents leave traces, and the chain of evidence is complete

Best Practice Tips

• Keep records of at least 3 methods of contact
• Keep trying for 30-60 days
• Note the time record (date, number of times)
• Keep copies of all electronic evidence and submit them at any time in case of challenge by the examiner or PTAB

If the USPTO believes that reasonable efforts are insufficient, it may lead to corrections, delays in authorization, or after authorization, procedural defects may be used by others to initiate invalidation challenges. Practical experience can be summarized in one sentence: it is not about proving that you cannot find the inventor, but proving that you are really trying hard to find the inventor.