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Date Published

Where there are a number of solutions to a problem, and the claimed solution has advantages over the other solutions, the issue arises of whether the person skilled in the art would have inevitably chosen that solution over the others.

Similarly, where the invention claimed is a selection from a known field, and there are advantages in that selection, examiners must determine whether the person skilled in the art would have inevitably chosen that selection.


  • the person skilled in the art would have adopted the particular solution, or chosen the particular selection, on the basis of a special inducement; and

  • there is no practical difficulty in implementing the particular solution, or in producing the selection, claimed;

the claim lacks an inventive step.

Special inducements occur when:

  • the prior art teaches towards the solution;

  • when the common general knowledge teaches towards the solution, or teaches away from the other solutions; or

  • when the other solutions are impractical.

Note: Where there is a special inducement to a single solution, the bonus effect is applicable (see Bonus Effect).

Blanco White Patents for Inventions (4th Edition) 1974 at pages 168-169, summarises the general test for an obvious selection based on special inducement as:

"The test of obviousness in such a case may then, it would seem, be put in the following form: Was it obvious to any skilled chemist, in the state of chemical knowledge existing at the date of the patent, that any substances within the claim would be likely to present a sufficient improvement over those previously made to justify the expenditure (of time and money) needed for their investigation? If this would not be obvious, then the invention should be patentable if it can be properly claimed."

It is not necessary to establish that success is certain or "clearly predictable", provided the person skilled in the art would be directed to a particular solution and it was clear to the person skilled in the art that it might well produce a solution to the problem  - see Wellcome Foundation Ltd v VR Laboratories (Aust) Pty Ltd (1981) 148 CLR 262 at 267.

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