What is the purpose of the “substantial new question of patentability” requirement in reexamination?

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 “substantial new question of patentability” requirement serves to protect patentees from unnecessary reexaminations. MPEP 2244 explains:

“The substantial new question of patentability requirement protects patentees from having to respond to, or participate in unjustified reexaminations.”

This requirement ensures that reexaminations are only conducted when there is a legitimate basis for questioning the validity of the patent, based on new or newly applied prior art.