What are Markush groupings and how do they affect unity of invention?
What are Markush groupings and how do they affect unity of invention?
Markush groupings are a way of claiming alternatives in patent applications, which can have implications for unity of invention. MPEP 1850 provides guidance on this:
“Alternative forms of an invention may be claimed either in a plurality of independent claims, or in a single claim. In the latter case, the presence of the independent alternatives may not be immediately apparent. In both cases, however, the same criteria should be applied in deciding whether there is unity of invention.”
Regarding Markush groupings specifically:
- A Markush grouping is considered to have unity of invention when the alternatives share a common structure or belong to a recognized class of compounds.
- The common structure must be a significant structural element shared by all alternatives.
- If the common structure is not novel, the Markush group may lack unity of invention.
- The ISA may require the applicant to restrict the claims to a single invention if unity is lacking.
For example, a claim to “A compound of formula (I)” followed by a Markush grouping of various chemical structures would be examined for a common structural element that contributes to the inventive step. If such a common element exists, unity of invention may be present despite the alternative structures.
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