MPEP 804: Double Patenting

Answer in brief

MPEP 804 prevents an applicant from getting more than one patent on the same invention, or on obvious variations of it. Statutory (same invention) double patenting under 35 U.S.C. 101 cannot be overcome by a terminal disclaimer. Nonstatutory, or obviousness-type, double patenting can be.

What MPEP 804 covers

Double patenting protects against unjustified extension of patent term and harassment by multiple assignees.

Statutory: the claims are identical in scope; overcome only by canceling or amending claims.
Nonstatutory: the claims are not identical but not patentably distinct; overcome with a terminal disclaimer under 37 CFR 1.321(c).
35 U.S.C. 121 bars nonstatutory double patenting rejections against divisionals filed because of a restriction (804.01).

How examiners use it

The rejection compares claims of the application to claims of a commonly owned patent or application.

On the patent bar

Know which type a terminal disclaimer can fix and the § 121 safe harbor.

Read the full text

Official title: Definition of Double Patenting [R-07.2022].

Read MPEP 804 in full on Wysebridge ↗

Or at the source: USPTO MPEP § 804.

Questions & answers

Can a terminal disclaimer overcome statutory double patenting?

No. A terminal disclaimer overcomes only nonstatutory (obviousness-type) double patenting. Statutory double patenting requires canceling or amending the claims.

Sources for this entry

USPTO — MPEP § 804 USPTO
Official text of this section, Ninth Edition, Revision 01.2024.
Wysebridge MPEP Center Wysebridge (publisher of this site)
The full MPEP (9th Ed., Rev. 01.2024) free to read, with Wysebridge's estimated patent bar weight for each chapter.

Practical guidance is original editorial content. Company-published figures are the company's own claims and are labeled as such.

Continue this reading path

MPEP 1490: Disclaimers and Terminal Disclaimers MPEP 803: Restriction Requirements

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Cite or share this entry

MPEP.net. “MPEP 804: Double Patenting.” Wysebridge Reference. Content reviewed 9 November 2026.
https://mpep.net/mpep-804/