How does the “written description” requirement relate to the enablement requirement?

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 written description requirement is distinct from, but related to, the enablement requirement in patent law. As stated in MPEP 2304.02(d):

“The written description requirement is separate and distinct from the enablement requirement. Ariad Pharm., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1340, 94 USPQ2d 1161, 1167 (Fed. Cir. 2010) (en banc).”

While enablement focuses on teaching how to make and use the invention, the written description requirement ensures that the inventor has actually possessed the claimed invention at the time of filing. Both requirements must be satisfied for a valid patent application.