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In considering whether or not a claimed invention is obvious, examiners will necessarily be presented with the problem at hand, as well as the solution to that problem (the claimed invention).

However, examiners should remember that the question of obviousness is to be answered by adopting the position of the person skilled in the art seeking to find a solution to the problem, and not by ex post facto reasoning which involves taking the known solution and working backwards to the problem by a succession of apparently easy steps. As stated in Palmer v Dunlop Perdriau Rubber Co Ltd (1937) 59 CLR 30 at page 61:

"It is frequently possible to take, as it were, a patent to pieces, and then, beginning with one piece, to show how, in order to obtain one result, step A must be taken; in order to obtain another particular result, step B must be taken - and so on until one has the whole combination for which inventive quality is claimed. If the analysis is taken into sufficient detail, every single step in the development of an invention, taken separately, can be shown to be obvious.

But, in the present case, the evidence of the expert witnesses for the defendant is really a reconstruction of an inventive process step by step, each step, when it is known that it must be taken in a certain direction, being obvious enough in itself."

Examiners should note that the inclusion of any part of the solution in the phrasing of the problem could also result in an ex post facto analysis of inventive step.

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