35 U.S.C. 103 Conditions for patentability; non-obvious subject matter.
(a) A patent may not be obtained though the invention is not identically disclosed or described as set forth in section 102 of this title, 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.

A large part of the problem with the 103(a) statute is its lack of clarity, a common legislative failure - 103(a) manifestly fails to define obviousness, the very subject it purports to legislate.

Not to put too fine a point on it, but anyone who complains about activists courts suffers an abject lack of historical perspective. The only interpretive power the courts have owes to the failure of the Constitution and legislation to be explicit. Of course, drafting laws has been rightfully likened to making sausage - one may be more at ease with the product not knowing the details of how it got there.

One may argue that the Constitution is wonderful because it offers breathing room for interpretation, adjusting for changing social mores through time. But one might be wrong to argue that, as one could more reasonably argue that the Constitution would have been a much better document if it had more clarity as to the power of the State, and of intrinsic individual freedoms from the State. Those are, after all, the clear boundary lines that should have been drawn. Of course, the U.S. Constitution was a hack job compromise between Federalists sanctioning the power of the State over individual freedom, and truer democrats. The Federalists got much of the upper hand, and America has come a long way, especially since 9/11, to becoming the police state that the more enlightened founding fathers dreaded. But I digress, as well as myself perhaps indulging in some impermissible hindsight here....

Back to 103(a) - the courts have fairly consistently ruled that a documentation trail must exist for obviousness; hand-waving with nothing of substance to point to about what the average technologist knew at the time doesn't cut it, nor should it. What a concept; yet that too draws controversy from the dimmer bulbs who are too easily liquored up on fuzzy logic (using the term 'logic' loosely). Yet, time and again, I encounter hand-waving combinations as a basis for claim rejection from patent examiners.

The mere fact that references can be combined or modified does not render the resultant combination obvious unless the prior art also suggests the desirability of the combination. In re Mills, 916 F.2d 680, 16 USPQ2d 1430 (Fed. Cir. 1990)

A statement that modifications of the prior art to meet the claimed invention would have been " 'well within the ordinary skill of the art at the time the claimed invention was made' " because the references relied upon teach that all aspects of the claimed invention were individually known in the art is not sufficient to establish a prima facie case of obviousness without some objective reason to combine the teachings of the references. Ex parte Levengood, 28 USPQ2d 1300 (Bd. Pat. App. & Inter. 1993). See also In re Kotzab, 217 F.3d 1365, 1371, 55 USPQ2d 1313, 1318 (Fed. Cir. 2000)

“Our case law makes clear that the best defense against the subtle but powerful attraction of a hindsight-based obviousness analysis is rigorous application of the requirement for a showing of the teaching or motivation to combine prior art references.” Dembiczak, 175 F.3d at 999; see also Ruiz, 234 F.3d at 665 (explaining that the temptation to engage in impermissible hindsight is especially strong with seemingly simple mechanical inventions). This is because “[c]ombining prior art references without evidence of such a suggestion, teaching, or motivation simply takes the inventor’s disclosure as a blueprint for piecing together the prior art to defeat patentability—the essence of hindsight.” Dembiczak, 175 F.3d at 999. Therefore, we have consistently held that a person of ordinary skill in the art must not only have had some motivation to combine the prior art teachings, but some motivation to combine the prior art teachings in the particular manner claimed. See, e.g., In re Kotzab, 217 F.3d 1365, 1371 (Fed. Cir. 2000) (“Particular findings must be made as to the reason the skilled artisan, with no knowledge of the claimed invention, would have selected these components for combination in the manner claimed.”); In re Rouffet, 149 F.3d 1350, 1357 (Fed. Cir. 1998) (“In other words, the examiner must show reasons that the skilled artisan, confronted with the same problems as the inventor and with no knowledge of the claimed invention, would select the elements from the cited prior art references for combination in the manner claimed.”). Teleflex v. KSR International, 04-1152 (CAFC 2005).