Widely criticized US standard for Obviousness of an invention for patent purposes. While novelty requires the showing of the complete claimed invention in a single reference (i.e., an item of prior-art), obviousness can be shown by combining references to show that they add up to the invention.
The TSM test, established by the Federal Circuit requires evidence of some reason to combine various references that teach the elements of the invention, as claimed. Typically, the Federal Circuit holds that evidence needs to be found by showing that the references come from an almost identical field or that there was some suggestion integral to the references that would lead (motivate) a reader to think of combining them.
The TSM test sets a very high hurdle for an obviousness determination. Ironically the Supreme Court’s opinion is rather vague too, and while suggesting that TSM should allow broader combinations of prior art, set no clear standard for what should or should not be combined. Therefore it is anticipated that changes resulting from KSR will be based on Federal Circuit precedents, which have not, hither-to-fore, been a beacon of clarity on obviousness issues either.