USPTO Manual on Patent Examining Procedure (MPEP) Section 2143 describes exemplary rationales for supporting an obviousness rejection.  In stating these exemplary rationales, the MPEP relies, in part, on the U.S. Supreme Court's decision in KSR International Co. v. Teleflex Inc., 550 US 398 (2007). 

In Crocs Inc. v. I.T.C., 598 F.3d 1294 (Fed. Cir., February 24, 2010), the Federal Circuit reverses an International Trade Commission (ITC) finding that a patent on footwear is obvious.  The claimed invention is a shoe (e.g., a clog) held onto a person's foot by a foam strap riveted to a foam base of the shoe.  Id. at 1308.  The strap wraps behind and supports the achilles tendon.  Friction between the foam strap and the base holds the foam strap in place even when the foam strap is not in contact with the achilles tendon.  Id. at 1309.  The points of novelty include using a strap made of inelastic foam and using the friction between the foam strap and the base to hold the foam strap in place.  Id. at 1308 - 1310. 

The ITC relied on two prior art references:  1)  an Aqua Clog -- a base without a strap; and 2)  Aguerre, teaching a sandal with a flexible strap.  Although the Crocs opinion does not refer to the MPEP, it is instructive to note which of the MPEP's rationales would support the ITC's obviousness rejection and how the Federal Circuit's opinion would refute hypothetical rejections based on these MPEP rationales.   

Three MPEP's rationales that could have been used by the ITC are that the claimed invention:  1) Combines prior art elements according to known methods to yield predictable results; 2)  Substitutes one known element for another to obtain predictable results; and 3)  Is obvious based on some teaching, suggestion, or motivation in the prior art that would have led one of ordinary skill in the art to modify a prior art reference.  MPEP Section 1243, Rationales A, B, and G.  The Court's findings in Crocs would refute obviousness rejections under any of the above MPEP rationales.   

The first rationale under the MPEP would be that the claimed invention is just a combination of prior art elements according to known methods to yield predictable results.  MPEP 2143A.  Under this rationale, the prior art must include "each element claimed."  Id.  This rationale first fails because the ITC's prior art combination did not include the claimed foam strap.  Crocs at 1308.  This rationale also fails because the use of the foam strap "yields more than predictable results; thus it is non-obvious."  Id. at 1309 citing KSR, 550 U.S. at 417.

The second rationale under the MPEP would be that the claimed invention is just a simple substitution of one known element for another to obtain predictable results.  MPEP 2143B. This rationale first fails because one skilled in the art would not have considered a foam strap to be a reasonable substitution for the elastic strap of Aguerre.  "Rather, the prior art showed that foam was an unsuitable material for shoe straps."  Id. at 1308 - 09.  The MPEP rationale also fails because using the foam strap instead of Aguerre's elastic strap yields more than predictable results.  An elastic strap is always in contact with the achilles tendon pushing the foot forward into the shoe.  The foam strap is not in continuous contact and "facilitates a loose anatomical fit that makes the claimed invention more comfortable than prior art products." Crocs at 1309.

The third rationale under the MPEP would be that the some teaching, suggestion, or motivation in the prior art would have motivated one skilled in the art to modify a prior art reference.  MPEP 2143G. But the Federal Circuit found that, "The record shows that the prior art would actually discourage and teach away from the use of foam straps."  Crocs, at 1308. 

Thus, all of the MPEP rationales that could have been used to support the ITC's obviousness rejection fail under the Court's findings in Crocs.  Thus, Crocs is instructive about the types of arguments and evidence that can be used to overcome an obviousness rejection under the MPEP.