What is the difference between ‘consisting of’ and ‘comprising’ in Markush groups?
The choice between ‘consisting of’ and ‘comprising’ in Markush groups is crucial as it affects the scope of the claim. According to the MPEP 2173.05(h):
“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.”
‘Consisting of’ creates a closed group, limiting the claim to only the listed alternatives. ‘Comprising’, on the other hand, creates an open group that may include unlisted elements. The MPEP advises:
“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.”
Therefore, ‘consisting of’ is generally preferred for Markush groups to ensure clarity and definiteness.
To learn more: