How does AIA 35 U.S.C. 102(a)(1) treat non-claimed subject matter in a patent?

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), even subject matter described but not claimed in a patent can be considered prior art. The MPEP states:

“Although an invention may be described in a patent and not claimed therein, the grant date would also be the applicable prior art date for purposes of relying on the subject matter disclosed therein as ‘described in a printed publication,’ provided that the patent was made available to the public on its grant date.”

This means that any subject matter disclosed in a patent, whether claimed or not, can potentially be used as prior art against a later invention, as long as the patent was publicly available on its grant date.