How does the AIA define “effective filing date” for a claimed invention?

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 America Invents Act (AIA) defines the “effective filing date” for a claimed invention as the earliest of:

• The actual filing date of the patent or application containing the claimed invention; or
• The filing date of the earliest application for which the patent or application is entitled to claim a right of priority or the benefit of an earlier filing date under 35 U.S.C. 119, 120, 121, 365, or 386.

This definition is provided in MPEP 2152.01, which states:

“The effective filing date of a claimed invention is determined on a claim-by-claim basis and not an application-by-application basis. It is possible for different claims in a patent or application to have different effective filing dates.”

Understanding the effective filing date is crucial for determining prior art and assessing patentability under the AIA.