In order to obtain a patent, the invention must be non-obvious. While this of course makes sense, distinguishing what is obvious from what is not can be difficult. Often, hindsight obstructs a fact-finder's mind when viewing the already-conceived invention. A common sense response such as "if it were so obvious, then why has no one done it before" can be effective in day to day conversations, but is generally ignored by the Patent Office. Some examiners at the USPTO simply love to utilize the inventor's own teachings to bootstrap improper rejections.
While there is various case law admonishing such hindsight reasoning, not all examiners are deterred. So, whenever the Federal Circuit provides some catchy phrases on this point, it is good for patent prosecution experts to take note of them and add them to their bag of tricks. Some examples are Judge Markey's famous quotes in the GORTEX case referring to the "attraction of the siren hindsight" and the admonishment not "to fall victim to the insidious effect of a hindsight syndrome wherein that which only the inventor taught is used against its teacher."
A recent case (Millennium Pharmaceuticals, Inc.) provides another good reminder, albeit with not quite the same eloquence of Judge Markey. In Millennium, Judge Newman directly addresses the hindsight approach taken by the District Court and writes that the "inventor’s own path itself never leads to a conclusion of obviousness; that is hindsight." The obviousness statute (Section 103) itself makes this clear when it states that "[p]atentability shall not be negatived by the manner in which the invention was made." See previous posts here and here that also touch on hindsight.
So, the next time an Examiner bases obviousness reasoning using the teachings of the inventor, confront the issue directly and point the Examiner to the statue and controlling case law that makes clear that "the path that leads an inventor to the invention is expressly made irrelevant to patentability by statute.” Life Techs., Inc. v. Clontech Labs., Inc., 224 F.3d 1320, 1325 (Fed. Cir. 2000).