How does the USPTO determine if subject matter is interfering?

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 USPTO determines if subject matter is interfering by examining the claims of different applications or patents. According to MPEP 2301.03:

An interference exists if the subject matter of a claim of one party would, if prior art, have anticipated or rendered obvious the subject matter of a claim of the opposing party and vice versa.

To make this determination, examiners compare the claims and assess whether:

• The claims are patentably indistinct from each other
• There is common subject matter between the applications or patents
• The claims would anticipate or render obvious each other if considered as prior art

This process ensures that only one patent is granted for the same inventive concept.