How does changing the principle of operation of a reference affect obviousness?

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Source: FAQ (MPEP-Based) BlueIron Update: 2024-09-30 10 Rules 5 Related FAQs 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 principle of operation of a prior art reference can negate an obviousness rejection. As stated in MPEP 2143.01 , “If the proposed modification or combination of the prior art would change the principle of operation of the prior art invention being modified, then the teachings of the references are not sufficient to render the claims prima facie obvious.” This principle, established in cases like In re Ratti , ensures that obviousness rejections are based on combinations that maintain the fundamental functioning of the prior art references. Related Rules from the Manual of Patent Examining Procedure 10 rules Collapse Modification Changing Principle of Operation Not Obvious MPEP 2143.01 Modification Changes Principle of Operation Requires Reconstruction MPEP 2143.01 Combination of Prior Art with Motivation Required for Obviousness MPEP 2143.01 Modification Would Make Prior Art Inoperable MPEP 2143.01 Permitted Inventor’s Motivation to Combine Prior Art Required MPEP 2143 Combination of Prior Art Requires Articulated Reasoning MPEP 2143 Requirement for Nonobvious Combination of Prior Art Elements MPEP 2143 Substituting Equivalent Methods Is Prima Facie Obvious MPEP 2143 Motivation to Modify Reaction Time MPEP 2143 Motivation to Combine Prior Art Must Exist MPEP 2143 Other Related FAQs 5 FAQs Collapse Is the ability to combine references sufficient to establish obviousness? How should conflicting teachings in prior art references be handled? What is the significance of the &#8220;intended purpose&#8221; of prior art in obviousness determinations? How does the &#8220;proposed modification cannot change the principle of operation&#8221; affect obviousness determinations? What is the s...