There is a misconception that a patent can be circumvented by a modification of a product by 10 per cent or 20 per cent. In reality, if the wording defining a part in a patent claim covers a functionally equivalent variation of that part in a different product, there is infringement of the patent (if all other parts are the same). In last month's Full Federal Court decision on an Australian innovation patent for a grain bin, the main difference between the patented bin and a rival bin was a deep open V-cut in a side wall instead of a hole for access to a grain outlet gate on the other side of the wall.

There's a patent for that

Australian Keg Company Pty Ltd was awarded an innovation patent for its animal feed storage bin.  The bin had upper and base modules, one fitting into the other, as shown below. The upper module was a cube with pyramid, which fitted upside-down into the base, which was a hollow open-topped cube, with angled support walls to cradle the pyramid. The star in the drawing below shows the location of an access recess in a base module wall to reach a grain outlet gate. The Keg patent claim did not use 'hole' or 'recess', but said the base was 'adapted to provide access to the outlet through the exterior side wall of the base'. 

The patent claim had 15 features. If the respondent's Stor-Cube did not take one of the features, then there would be no infringement.

Click here to view image.

Real cut-through

A picture of the Stor-Cube is below. Two points of difference were argued by the respondents.

First, the outlet of the Stor-Cube appeared to be mounted in a lower part of the side wall of the upper module but the Full Federal Court agreed that it was still mounted in the 'bottom' of that upper module, taking that feature of the claim. 

The most interesting argument related to the 'through the…wall' feature. There was a V-cut in the base module wall. Did that V-cut actually provide access to the outletthrough the base wall or did it do something else? The Stor-Cube owners argued that it gave access to the outlet above and therefore over the base wall.

Click here to view image.

Victory of function over form

The trial judge, Justice Dowsett, found, as have many others, that when construing the wording of patent claims it is not just the definition of one word but whole phrases and indeed the context of the entire claim that matters. The main argument was therefore too focussed on the word 'through'. With the Court's broader and functional approach, it was found that the claimed base wall was defined to surround the upper portion, and that wall was 'adapted' (Fit, adjust, make suitable) to provide 'access' (a way or means of approach) 'through'  (from one end, side or surface to the other or opposite…by passing within it… in to, at one end, side etc and out of at the other).

Justice Dowsett said: 'In my view the reference to access “through the wall” identifies an outcome to be achieved rather than a limit on the method to be adopted. I consider that the expression “through the wall” includes any direct means for passing from one side to the other.' 

The Full Court agreed with that approach, in that an open cut in the base is bounded by the walls on three sides, and a small strip of plastic to close the cut would make no real difference to the function and would still be caught by the wording of the claim. In any event there were flanges to hold the upper portion in place and one had to go from one side to the other of those to get to the outlet. They did not mention the trial judge's useful analogy of 'passing through a canyon or the Suez Canal' even though the canal has an open roof; ultimately the Stor-Cube appeal was dismissed and infringement was found.

Kernels of wisdom

Patents can protect the function of an invention and therefore a critical part of the drafting process is to work with your patent attorney to generate functional phrases defining what the invention does.

Mathematically-enhanced readers will calculate that without access through the wall, the Stor-Cube might have been different from the patent by 6.67 per cent. If the Stor-Cube did not have that feature, that would have been enough to avoid infringement, but that does not prove that a variation of 6.67 per cent avoids a patent. The only test was whether the Stor-Cube variation was functionally equivalent to the phrasing used in the patent claim.