What does the MPEP say about subjective terms in patent 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 addresses subjective terms in patent claims in MPEP 2173.05(b). Subjective terms can be problematic because they may not have a well-defined or universally accepted meaning. The MPEP states:

“When a subjective term is used in the claim, the examiner should determine whether the specification supplies some standard for measuring the scope of the term, similar to the analysis for a term of degree. Some objective standard must be provided in order to allow the public to determine the scope of the claim.”

Examples of subjective terms include “aesthetically pleasing,” “unobtrusive manner,” and “not interfering substantially.” These terms can be indefinite if the specification doesn’t provide a clear standard for measuring them. The key is whether a person of ordinary skill in the art would be able to determine the scope of the claim with reasonable certainty based on the specification and the knowledge in the art.