Obtaining a patent for an invention requires the crossing of many statutory hurdles. One of the main statutory hurdles is to rebut any contentions by a patent examiner that an invention may be obvious (i.e., rebutting a prima facie case obviousness). Many strategies may be utilized to rebut a prima facie case of obviousness.
By way of background, a prima facie case of obviousness stems from 35 U.S.C. §103(a), which states that a “patent may not be obtained…if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains.” To establish a prima facie case of obviousness, patent examiners must provide a reason as to why a person skilled in the art would have modified the prior art or combined different prior art references to arrive at an invention. Examiners generally provide such rationale in the form of a formal communication from the U.S. Patent and Trademark Office (also referred to as an “Office Action”). Inventors or applicants will then have the opportunity to rebut the prima facie case of obviousness by replying to the Office Action.
One of the ways to rebut a prima facie case of obviousness would be to find evidence in the cited prior art references that discourages or dissuades others from arriving at the invention. For instance, one can refer to an excerpt from a cited prior art reference that discourages the skilled artisan to arrive at the invention. Commonly, such evidence is referred to as evidence that “teaches away” from the invention.
Another way to rebut a prima facie case of obviousness would be to prove that the invention combined certain known features from the prior art to yield unpredictable results. For instance, one may argue that the combination of two elements from the prior art provided a “synergistic” effect that would not have been predicted at the time of the invention. Such unpredictable results usually require the presentation of evidence in the form of experimental results.
In brief, many strategies exist for rebutting a prima facie case of obviousness. Whether or not such rebuttals will succeed will depend on many factors, including the nature of the invention (e.g., whether or not the invention yielded unpredictable results) and the teachings of the prior art (e.g., whether or not the prior art taught away from the invention).
 See KSR International Co. v. Teleflex Inc. (KSR), 550 U.S. 398, 418 (2007). Also see Manual of Patent Examination Procedure (M.P.E.P.) §2141(III).
 See M.P.E.P. §2141(IV)