The written description requirement requires a patent applicant to 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:
Each claim limitation must be expressly, implicitly, or inherently supported in the originally filed disclosure. Each claim must include all elements which applicant has described as essential or critical.
The Written Description Requirement is satisfied by the disclosure of such descriptive means as:
that fully set forth the claimed invention.
The scope of claims are examined as a whole giving the broadest reasonable interpretation in light of and consistent with the description. Factors considered when analyzing claims for compliance with the written description requirement include:
Does the specification show any embodiments that meet all the limitations of the claim reduced to practice? Note that reduction to practice is not required to meet the written description requirement.
An applicant may show possession of an invention by disclosure of drawings or structural chemical formulas that are sufficiently detailed to show that applicant was in possession of the claimed invention as a whole.
What is conventional or well known to one skilled in the art need not be disclosed in detail
A written description determination for genus claims (broad claims which cover more specific claims) includes analyzing whether the inventor was in possession of each claim drawn to a single embodiment or species first, and then for each claim drawn to a genus. Written description for a claimed genus may be satisfied through sufficient description of a representative number of species: