What are the guidelines for using “consisting of” in Markush claims?

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.

The MPEP provides specific guidelines for using “consisting of” in Markush claims in MPEP 2173.05(h). The section states:

“When materials recited in a claim are so related as to constitute a proper Markush group, they may be recited in the conventional manner, or alternatively. For example, if “wherein R is a material selected from the group consisting of A, B, C and D” is a proper limitation, then “wherein R is A, B, C or D” shall also be considered proper.”

This guidance indicates that “consisting of” is a conventional way to introduce a Markush group, but it’s not the only acceptable format. The key is to clearly indicate that the claim is limited to the listed alternatives. When using “consisting of,” it’s important to ensure that the group is closed and does not leave room for additional, unlisted elements.