When does a patent become prior art under AIA 35 U.S.C. 102(a)(1)?

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.

Under AIA 35 U.S.C. 102(a)(1), a patent generally becomes prior art on its grant date. The MPEP states:

“The effective date of the patent for purposes of determining whether the patent qualifies as prior art under AIA 35 U.S.C. 102(a)(1) is the grant date of the patent.”

However, there’s an exception for secret patents:

“There is an exception to this rule if the patent is secret as of the date the rights are awarded. […] In such situations, the patent is available as prior art as of the date the patent was made available to the public by being laid open for public inspection or disseminated in printed form.”

This means that for most patents, the grant date is the critical date for prior art purposes, but for secret patents, it’s when they become publicly available.