How should prior art figures be labeled in a patent application?

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.

When including prior art figures in a patent application, proper labeling is crucial. According to MPEP 608.02(g), prior art figures should be designated by a legend such as ‘Prior Art.’ This labeling is essential to distinguish prior art from the applicant’s invention.

If a prior art figure is not correctly labeled, patent examiners may use form paragraph 6.36.01, which states: Figure [1] should be designated by a legend such as –Prior Art– because only that which is old is illustrated. See MPEP § 608.02(g). This paragraph instructs the applicant to correct the labeling to comply with the MPEP guidelines.