“The Court of Appeals, finally, drew the wrong conclusion from the risk of courts and patent examiners falling prey to hindsight bias. A factfinder should be aware, of course, of the distortion caused by hindsight bias and must be cautious of arguments reliant upon ex post reasoning. … Rigid preventative rules that deny factfinders recourse to common sense, however, are neither necessary under our case law nor consistent with it.” p. 17

The above passage is curious. The mantra of avoiding “hindsight bias” has, in general, been directed to the analysis of the ultimate question of obviousness – which as everyone knows is a question of law, not fact. The KSR Court noted that Graham itself warned against a “temptation to read into the prior art the teachings of the invention in issue.” And the TSM test was intended to prevent the use of “hindsight bias.” But, there seems to be a disconnect here.

On the one hand, Graham talks about how the so-called “secondary considerations” of nonobviousness help to avoid the use of hindsight, and “to resist the temptation to read into the prior art the teachings of the invention in issue.” But, it seems to me that there are two different issues involved here. When the Graham court refers to avoiding the use of hindsight, it seems to me that they were referring to the use of hindsight in deciding the ultimate legal question of obviousness. The part about not reading the teachings of the invention into the prior art goes to an earlier step in the process – determining the scope and content of the prior art (which is a factual, not legal, undertaking). The improper use of hindsight is usually not an issue during that step of the analysis.

As for the TSM test, its purpose was to prevent the use of hindsight bias during the final step of the obviousness analysis – determining, as a matter of law, the ultimate question of obviousness based upon the earlier factual determinations. But, the question of what a particular reference taught or suggested was still viewed by the Federal Circuit (at least so they said) as a factual determination to be made by the factfinder.

So, if a strict application of TSM is no longer permitted, where is the line drawn between the obligations of the factfinder and those of the court? The KSR Court talks about how rigid application of TSM will “deny factfinders recourse to common sense.” But, how does the factfinder exercise their “common sense” on the issue of obviousness without crossing the line into the realm of determining the ultimate LEGAL issue of obviousness? The KSR Court clearly states that the factfinder should be permitted to use their common sense, but where do factfinders do this within the framework of the obviousness analysis?