How does the MPEP address changes in numerical range limitations?

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 changes in numerical range limitations in section 2163.05. It states that “[a] claim that omits an element which applicant describes as an essential or critical feature of the invention originally disclosed does not comply with the written description requirement.” This principle applies to changes in numerical range limitations.

The MPEP provides specific examples:

• In In re Wertheim, the ranges of “between 35% and 60%” and “between 25% and 60%” were held to be new matter since the specification as originally filed failed to provide support for the claimed ranges.
• However, in Ex parte Grasselli, a claim limitation of “less than 25% by weight” was held to be supported by the originally filed disclosure of “between 15% and 70% by weight.”

These examples illustrate that the written description requirement for changes in numerical range limitations depends on whether the original disclosure provides sufficient support for the new range.