What constitutes a violation of the written description requirement when changing claim scope?

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.

Changing the scope of claims after filing can violate the written description requirement of 35 U.S.C. 112(a) in several ways:

• Broadening claims by removing limitations
• Narrowing claims by adding unsupported elements
• Altering numerical range limitations
• Using claim language not synonymous with the original disclosure

As stated in MPEP 2163.05: “The failure to meet the written description requirement of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, commonly arises when the claims are changed after filing to either broaden or narrow the breadth of the claim limitations, or to alter a numerical range limitation or to use claim language which is not synonymous with the terminology used in the original disclosure.”