When does omitting a limitation violate the written description requirement?

Omitting a limitation can violate the written description requirement when the omitted element is described as essential or critical to the invention in the original disclosure. The MPEP 2163.05 states:

“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 is illustrated in case law, such as Gentry Gallery, Inc. v. Berkline Corp., where claims were invalidated for removing the location of a control means that was described as the “only possible location” in the original disclosure.

To learn more:

• written description
• claim amendments
• omitting limitations
• essential features
• critical features