The first serious consideration of section 7(4) of the Patents Act 1990 relating to innovative step, the decision of Gyles J in Delnorth Pty Ltd v Dura-Post (Aust) Pty Ltd  FCA 1225, gives a somewhat unexpected interpretation of the phrase “substantial contribution to the working of the invention”.
Gyles J commences with a concise explanation of the approach to be taken in assessing innovative step, consistent with recent approaches to the question of inventive step, noting that:
There is no need to search for some particular advance in the art to be described as an innovative step which governs the consideration of each claim. The first step is to compare the invention as claimed in each claim with the prior art base and determine the difference or differences. The next step is to look at those differences through the eyes of a person skilled in the relevant art in the light of common general knowledge as it existed in Australia before the priority date of the relevant claim and ask whether the invention as claimed only varies from the kinds of information set out in s 7(5) in ways that make no substantial contribution to the working of the invention. It may be that there is a feature of each claim which differs from the prior art base and that could be described as the main difference in each case but that need not be so. Section 7(4), in effect, deems a difference between the invention as claimed and the prior art base as an innovative step unless the conclusion which is set out can be reached.
His Honour then considered the background to the introduction of innovation patents, including the High Court decision in Griffin v Isaacs from which the phrase “substantial contribution to the working of the invention” is derived, concluding that
The focus is upon working of the invention (as claimed) not to the degree or kind of variation from the kinds of information set out in s 7(5). In other words, the variation from the kinds of information might be slight but, if a substantial contribution is made to the working of the invention, then there is an innovative step.
The judgment then turns to the presence or absence of innovative step in this particular instance, with Gyles J noting at  that:
As I have endeavoured to explain, the question is not whether flexible sheet steel is better than flexible PVC – it is certainly different. It cannot be seriously argued that the material sheet spring steel does not make a substantial contribution to the working of the roadside post claimed in each claim
And again at :
The different material contributes substantially to the manner in which that invention as claimed performs. As I have said earlier, it is not a question as to whether these claims are better than the disclosure by Kennedy, or whether it was obvious to move from Kennedy to this invention. Therefore, there is an innovative step over Kennedy.
Accordingly, the test applied by Gyles J appears to be whether the feature, which varies from the prior art, in and of itself makes a substantial contribution to the working of the invention, rather than whether the nature of the variation, the extent to which that feature differs from the prior art, makes such a contribution. Indeed it appears that the feature which varies may be inferior to that disclosed in the prior art and the invention nevertheless involve an innovative step.
The judgement also implicitly confirms that all prior art information may be relied upon in assessing innovative step provided it is publicly available, in contrast with inventive step where that information must satisfy the requirement of section 7(3).