How are Markush claims examined for patentability?

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.

Markush claims are examined for patentability like other claims, but with some specific considerations:

1. The examiner first determines if the Markush grouping is proper.
2. If improper, a rejection based on an improper Markush grouping is made.
3. The claim is then examined for all other conditions of patentability (e.g., 35 U.S.C. 101, 102, 103, 112, and nonstatutory double patenting).
4. The search need not be extended to species that fall outside a proper Markush grouping.

The MPEP states: The claim should be examined for patentability with respect to all other conditions of patentability (e.g., 35 U.S.C. 101, 102, 103, 112, and nonstatutory double patenting).

It’s important to note that even if an improper Markush grouping rejection is made, the examiner should still examine the claim for other patentability issues to promote compact prosecution.