The USPTO rejects patent applications based on "prior art" either because the claims of the application are anticipated (all claim elements appear in a single prior art reference) or because of the claims of the application are obvious.  To show that a patent claim is obvious the USPTO may establish a prima facie case of obviousness by combining the teachings of two or more prior art references and/or by proposing a modification to a prior art reference.

MPEP 2145(IV) states that, "One cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references," citing In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).  This statement does not make sense because if the references as combined/modified still fail to recite or suggest all of the elements of an applicant's claim, then it would appear that the USPTO has not stated a prima facie case of obviousness.

A recent Federal Circuit case suggests that the MPEP's blanket statement is at best an oversimplification.  In In re Glatt Air Technologies, 630 F.3d 1026, 2011 U.S. LEXIS 79 (Fed. Cir., January 5, 2011), the Federal Circuit reversed a finding by the Board of Patent Appeals and Interferences (the "Board") that a patent claim was obvious.  Specifically, the Court held that the USPTO had failed "to make a proper prima facie case of obviousness."  Id. *10 (Page cites are to LEXIS pagination). 

Without getting into the details of the invention, the disputed claim was written in Jepson format, where the preamble before the words "the improvement comprising" is admitted prior art.  Id. *4 & 9.  The USPTO rejected the disputed claim 5 over a combination of the preamble of Claim 5 and a reference called Naunapper.  Id. *5.  The Board affirmed an Examiner's rejection of claim 5 on obviousness grounds.  The Board stated that Naunapper "would inherently or necessarily be capable of performing the same function recited by the claimed shielding means"  Id. *7 (Quoting the Board). 

In finding that the Board had failed to state a prima facie case of obviousness, the Court did not address whether the Board could properly combine the references (the preamble and Naunapper).  Instead, in apparent contradiction to MPEP 2145(IV), the Court focused on whether Naunapper -- a single reference -- taught a claimed function:  "shielding."  The Court found that, "The Board's finding that Naunapper teaches shielding the nozzle to prevent particles from prematurely entering into the initial spray pattern is not supported by substantial evidence because Naunapper does not teach shielding *** Because Naunapper does not teach shielding, we conclude that the Board has failed to make a proper prima facie case of obviousness."  Id. (Bold added).

Therefore, In re Glatt Technologies appears to be an example of where the Court did find nonobviousness by attacking a reference individually -- specifically, the Court held that the USPTO failed to state a prima facie case of the obviousness of claim 5.  Although neither MPEP 2145(IV), Keller, nor Merck were cited, this case appears to do exactly was MPEP 2145(IV) says cannot be done -- to "show nonobviousness by attacking references individually where the rejections are based on combinations of references."  MPEP 2145 (IV). There are indeed many cases where an applicant needs to argue that references cannot be combined or modified as proposed by the USPTO.  But In re Glatt Technologies appears to be a case where it was sufficient to show that one of the references did not teach what the USPTO found that it did.