How does the MPEP address the use of “consisting of” vs. “comprising” in alternative limitations?

The MPEP addresses the use of “consisting of” vs. “comprising” in alternative limitations in MPEP 2173.05(h). The distinction is crucial for the definiteness and scope of the claim:

“A Markush grouping is a closed group of alternatives, i.e., the selection is made from a group ‘consisting of’ (rather than ‘comprising’ or ‘including’) the alternative members.”

Key points to understand:

• “Consisting of”: This phrase creates a closed list of alternatives. It limits the claim to only the listed elements.
• “Comprising” or “Including”: These terms create an open-ended list, which can lead to indefiniteness issues.
• Indefiniteness concern: The MPEP warns, “If a Markush grouping requires a material selected from an open list of alternatives (e.g., selected from the group ‘comprising’ or ‘consisting essentially of’ the recited alternatives), the claim should generally be rejected under 35 U.S.C. 112(b) as indefinite because it is unclear what other alternatives are intended to be encompassed by the claim.”

Using “consisting of” in alternative limitations helps ensure clarity and definiteness in patent claims, while “comprising” may introduce ambiguity about the scope of the alternatives.

To learn more:

• consisting of
• comprising
• alternative limitations
• Markush grouping
• patent claims
• MPEP 2173.05(h)