What is the “single means claim” and why is it often rejected?

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.

What is the “single means claim” and why is it often rejected?

A “single means claim” is a claim that recites a single means plus a function. These claims are often rejected due to lack of enablement. The MPEP 2164.08(a) explains:

“A single means claim, i.e., where a means recitation does not appear in combination with another recited element of means, is subject to an enablement rejection under 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph.”

Single means claims are typically rejected because they attempt to cover every conceivable means for achieving a specific function, which is often considered too broad to be fully enabled by the specification. Such claims would likely require undue experimentation to practice the full scope of the invention, violating the enablement requirement. To avoid this issue, applicants should generally use multiple means or steps to define their inventions more specifically.