How does the AIA affect the critical reference date?

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) significantly changed the determination of the critical reference date for U.S. patents and patent application publications. MPEP 2136.03 explains:

“AIA 35 U.S.C. 102(d) provides that if the U.S. patent, U.S. patent application publication, or WIPO published application names another inventor and was effectively filed before the effective filing date of the claimed invention, it is prior art under AIA 35 U.S.C. 102(a)(2).”

Key changes under the AIA include:

• The critical reference date is now the “effectively filed” date, which can be either the actual filing date or the filing date of an earlier application to which priority or benefit is claimed.
• The concept of “effective filing date” replaces the pre-AIA focus on the earliest U.S. filing date.
• The AIA eliminated the distinction between U.S. and foreign priority documents for prior art purposes.

These changes apply to applications and patents subject to the first-inventor-to-file provisions of the AIA.