How are range limitations evaluated under the written description requirement?

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.

Range limitations are evaluated based on what one skilled in the art would consider inherently supported by the original disclosure. The MPEP 2163.05 provides guidance:

“With respect to changing numerical range limitations, the analysis must take into account which ranges one skilled in the art would consider inherently supported by the discussion in the original disclosure.”

Key considerations include:

• The ranges explicitly described in the specification
• Specific examples within the range
• Whether the new range limitation has support throughout its entire scope

For example, in In re Wertheim, a new claim limitation of “at least 35%” did not meet the description requirement when the original specification described a range of “25%-60%” because “at least” had no upper limit. However, a limitation to “between 35% and 60%” did meet the requirement.