How does functional language in original claims affect written description requirements?
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.
Functional language in original claims can lead to written description issues if not properly supported by the specification. According to MPEP 2163.03:
“[A]n adequate written description of a claimed genus requires more than a generic statement of an invention’s boundaries.”
This means that when claims use functional language to define the invention, the specification must provide sufficient detail on how the function is performed or the result is achieved. If the specification lacks this detail, it may not meet the written description requirement, even for original claims.
To avoid issues, inventors should ensure their specifications include:
- Detailed descriptions of how claimed functions are performed
- Specific examples or embodiments that illustrate the functional language
- Sufficient information for a person skilled in the art to understand that the inventor possessed the full scope of the claimed invention