Defending against an obviousness attack at the PTAB or rejection
by a USPTO examiner can be tricky. The Supreme Court in
KSR v. Teleflex (2007) identified a number of rationales
(seven) to support a conclusion of obviousness. Most rationales
invoke the notion of predictability for the results yielded by the
combination of prior art references. The challenger gets to
pick and choose the rationale that fits best the claimed invention
and the prior art.
The trick for the patent applicant or owner is to find the right
tool within the non-obviousness toolkit to defend against the
challenge. It turns out that one such tool is an older
decision, still being applied today. The case is In re
Ratti (CCPA 1959). It stands for the proposition that,
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
