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…

How does the “proposed modification cannot change the principle of operation” affect obviousness determinations? This principle is a critical consideration in assessing the obviousness of a claimed invention. According to MPEP 2143.01(VI): “If the proposed modification or combination of the prior art would change the principle of operation of the prior art invention being modified,…