What is the nexus requirement in patent law?

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 nexus requirement in patent law refers to the need for a causal relationship between the claimed invention and the objective evidence of nonobviousness. As stated in MPEP 716.01(b):

“An applicant must show that the claimed features were responsible for the commercial success of an article if the evidence of nonobviousness is to be accorded substantial weight.”

This means that when presenting evidence of nonobviousness, such as commercial success or unexpected results, the applicant must demonstrate that these outcomes are directly related to the novel aspects of the invention, rather than other factors like marketing or unrelated features.