What is a Markush group in a patent claim?
A Markush group is a way of claiming a list of alternatively useable members in a patent claim. According to 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.”
Markush groups are typically used to claim chemical compounds, but can be used in other contexts as well. The MPEP notes that a Markush group may include a large number of alternatives without necessarily being indefinite under 35 U.S.C. 112(b). However, if the group is so expansive that a person skilled in the art cannot determine the metes and bounds of the claimed invention, it may be considered indefinite.
To learn more:
Topics:
MPEP 2100 - Patentability,
MPEP 2173.05 - Specific Topics Related To Issues Under 35 U.S.C. 112,
MPEP 2173.05 - Specific Topics Related To Issues Under 35 U.S.C. 112(B) Or Pre - Aia 35 U.S.C. 112,
Patent Law,
Patent Procedure,
Second Paragraph