What are the key considerations for “lists of alternatives” in patent claims?

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.

When dealing with lists of alternatives in patent claims, there are several key considerations outlined in MPEP 2173.05(h):

1. Proper Markush format: The MPEP states, “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.”
2. Indefiniteness: 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.”
3. Improper Markush grouping: The MPEP advises, “A Markush claim may be rejected under judicially approved ‘improper Markush grouping’ principles when the claim contains an improper grouping of alternatively useable members.”
4. Subgenus claims: The MPEP notes, “A claim may list alternative species or subgenera as a single member of a Markush group.”

Understanding these considerations is crucial for drafting clear and definite claims with alternative limitations.