Can a Markush claim be rejected for having an improper Markush grouping?

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.

Yes, a Markush claim can be rejected for having an improper Markush grouping. According to MPEP 803.02:

“If the Markush grouping was improper, a rejection on the basis of there being an improper Markush grouping should be made as described in MPEP § 2117.”

An improper Markush grouping exists when the alternatives defined by the Markush group do not share both a single structural similarity and a common use. The rejection should explain why the Markush grouping is improper and advise the applicant of the species that do not belong to a proper Markush grouping.

It’s important to note that this rejection is an appealable matter, not a petitionable one. The examiner typically uses form paragraph 8.40 to make this rejection. No Markush claim can be allowed until any improper Markush grouping rejection has been overcome or withdrawn, and all other conditions of patentability have been satisfied.