What are the potential issues with functional limitations in patent claims?

While functional limitations are allowed in patent claims, they can potentially raise issues of indefiniteness. The MPEP notes that “the use of functional language in a claim may fail ‘to provide a clear-cut indication of the scope of the subject matter embraced by the claim’ and thus be indefinite.”

Some potential issues include:

• Claims that merely recite a description of a problem to be solved or a function or result achieved by the invention may have unclear boundaries.
• Without reciting specific structure, materials, or steps, the claim may encompass all means or methods of resolving the problem.
• Functional limitations may not be adequately supported by the written description or may not be commensurate in scope with the enabling disclosure.

Examiners consider factors such as whether there’s a clear indication of claim scope, whether the language sets well-defined boundaries, and whether one of ordinary skill in the art would understand the claim’s scope from the functional language.

To learn more:

• functional limitations
• patent claims
• indefiniteness
• claim scope
• written description