What are the restrictions on amendments in patent reexamination?

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.

Amendments in patent reexamination are subject to several restrictions:

• They may not enlarge the scope of a claim of the patent or introduce new matter.
• Amended or new claims that broaden or enlarge the scope of a claim should be rejected under 35 U.S.C. 305.
• Amendments do not become effective in the patent until the reexamination certificate is issued and published.
• No amendment will be permitted where the certificate issues after expiration of the patent.

As stated in the MPEP: “Amended or new claims which broaden or enlarge the scope of a claim of the patent should be rejected under 35 U.S.C. 305.” This means that any amendment that expands the patent’s coverage is not allowed in reexamination.