What constitutes a ‘reasonable’ excuse for inactivity in the diligence period?

A ‘reasonable’ excuse for inactivity in the diligence period is context-dependent and evaluated on a case-by-case basis. The MPEP 715.07(a) provides guidance:

‘Reasonable excuses for inactivity include illness, employment obligations, military service, and activity on other applications or inventions.’

However, the USPTO emphasizes that these excuses must be properly explained and supported:

‘The work relied upon to show reasonable diligence must be directly related to the reduction to practice of the invention in question.’

To determine if an excuse is reasonable:

  • Consider the length of the inactivity period
  • Evaluate the nature of the excuse in relation to the invention’s complexity
  • Assess whether the inventor took steps to resume work as soon as possible
  • Examine if the excuse prevented all work or just slowed progress

Inventors should provide detailed explanations and, where possible, documentation to support any periods of inactivity during the diligence period.

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