What is the difference between absolute and equitable intervening rights?

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.

The main differences between absolute and equitable intervening rights are:

• Absolute intervening rights:
  • Apply automatically
  • Cover specific items made, purchased, or used before reinstatement
  • Allow continued use without additional court approval
• Equitable intervening rights:
  • Require court approval
  • May allow continued manufacture, use, or sale of additional products
  • Considered on a case-by-case basis

MPEP 2591 states: “The court must find that substantial preparation was made before the patent was reinstated for the amendment to permit continued practice of the subject matter claimed in the reissue patent.” This refers specifically to equitable intervening rights, highlighting the discretionary nature of their application.