MPEP 2143.01: Motivation to Combine or Modify

Answer in brief

MPEP 2143.01 governs the reason to modify or combine references. The motivation can come from the references, the knowledge of a person of ordinary skill, or the nature of the problem. A modification is not obvious if it would make the reference unsatisfactory for its intended purpose (2143.01(V)) or change its principle of operation (2143.01(VI)).

What MPEP 2143.01 covers

Motivation does not have to be stated in the references themselves.

The prior art must suggest the desirability of the combination, not merely that it could be made.
That references can be combined is not enough on its own.
Fact that the claimed invention is within the capabilities of one of ordinary skill is not, alone, enough.
2143.01(V): no suggestion to modify if the change renders the reference unsatisfactory for its intended purpose.
2143.01(VI): no suggestion to modify if the change would alter the reference's principle of operation.

How examiners use it

Applicants regularly argue (V) and (VI). The examiner must then show the modified reference still works for its purpose or that its operating principle is unchanged.

On the patent bar

Know the intended-purpose and principle-of-operation exceptions; both are frequent exam distractors.

Read the full text

Official title: Suggestion or Motivation To Modify the References [R-01.2024].

Read MPEP 2143 in full on Wysebridge ↗

Or at the source: USPTO MPEP § 2143.

Questions & answers

What is the principle of operation rule?

Under MPEP 2143.01(VI), if a proposed modification would change the basic principle under which the reference operates, the references are not sufficient to make the claims obvious.

Sources for this entry

USPTO — MPEP § 2143 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 2143: The KSR Rationales for Obviousness Teaching Away in the MPEP MPEP 2145: Rebutting an Obviousness Rejection

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Cite or share this entry

MPEP.net. “MPEP 2143.01: Motivation to Combine or Modify.” Wysebridge Reference. Content reviewed 9 November 2026.
https://mpep.net/mpep-2143-01/