How does the prior art regime affect reexamination proceedings?

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 prior art regime applicable to a reexamination proceeding generally depends on the filing date of the patent application. The MPEP states:

“The prior art regime under which the application for the patent was examined (the first-inventor-to-file prior art regime, or the first-to-invent prior art regime) will generally be applied in the reexamination of the patent.”

However, there are exceptions:

• For patents resulting from applications filed before March 16, 2013, the first-to-invent regime typically applies
• For patents resulting from applications filed on or after March 16, 2013, the first-inventor-to-file regime typically applies
• Rare situations may arise where the regime changes during reexamination, such as when a benefit claim to a pre-AIA application is added

It’s important to note that the applicable prior art regime can affect the scope and interpretation of prior art in the reexamination proceeding.