What are contingent limitations in patent claims and how are they interpreted?

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.

Contingent limitations in patent claims are conditions that may or may not occur, affecting the interpretation of the claim. The MPEP 2111.04 provides guidance on interpreting these limitations:

“The broadest reasonable interpretation of a method (or process) claim having contingent limitations requires only those steps that must be performed and does not include steps that are not required to be performed because the condition(s) precedent are not met.”

For method claims:

• If a condition is not required to occur, steps dependent on that condition are not required for the broadest reasonable interpretation.
• If a condition must occur, steps dependent on that condition are required.

For system or apparatus claims:

• The structure for performing the function must be present in the system, regardless of whether the condition is met.

Patent attorneys and examiners should carefully consider the claim type (method vs. system) when interpreting contingent limitations, as this can significantly impact the claim scope and patentability analysis.