Last updated: August 17, 2026

What Is the Written Description Requirement, and How Do I Satisfy It?

The written description requirement warrants that a patent applicant be in possession of the specific subject matter claimed as of the filing date of the patent application. Possession is shown by describing the invention, with all its claimed limitations. Although the applicant does not have to describe exactly the subject matter claimed, the description must clearly allow persons skilled in the art to recognize that the applicant(s) invented what is claimed. A description of what a material does, rather than what it is, usually is not sufficient.

All claims are subject to the written description requirement, including:

Original claims
New claims and amended claims
Claims asserting benefit of an earlier priority or filing date

Each claim limitation must be expressly, implicitly, or inherently supported in the originally filed disclosure. Each claim must also include all elements which the applicant has described as essential or critical.

The Written Description Requirement is satisfied by the disclosure of such descriptive means as:

Formulas
Words
Structures
Figures
Diagrams

Functional characteristics when coupled with a known or disclosed correlation between function and structure that fully set forth the claimed invention.

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