Patent Written Description

Adequately Describing an Invention

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:

• 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 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:

• 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.

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:

1. Actual reduction to practice:

   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.

2. Disclosure of drawings or structural chemical formulas:

   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.

3. Sufficient relevant identifying characteristics:
   1. Complete structure
   2. Partial structure
   3. Physical and/or chemical properties
   4. Functional characteristics when coupled with correlation between structure and function
4. Method of making the claimed invention.
5. Level of skill and knowledge in the art.

   What is conventional or well known to one skilled in the art need not be disclosed in detail

6. Predictability of the art.

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:

1. by showing an inverse function of the skill and knowledge in the art
2. by showing whether one of skill in the art would recognize necessary common attributes or features possessed by the members of the genus
3. in an unpredictable art, adequate written description of a genus which embraces widely variant species cannot be achieved by disclosing only one species within the genus