Justice Tamberlin reinforced in a patent decision handed down last week that Australian courts should take a common sense approach towards construing patent claims, rejecting the patentee’s arguments that the word ‘concrete’ in the patent claim could mean ‘plastic’.
The patent and the patent claim
Baygol was the owner of a patent for a method of making concrete footings for residential houses. Claim 1 set out the eight steps that were required to practise the invention, the fourth step requiring the positioning of ‘concrete spacers’ between a grid of hollow boxes.
The patent made it clear that the role of the concrete spacers was twofold:
to support steel reinforcing rods in their design position in the rows between the hollow boxes, a few centimetres above the ground, and
to hold the hollow boxes in position when concrete was subsequently poured over and between the hollow boxes.
The idea was that a concrete slab would be poured over the top of the grid of hollow boxes, but concrete would penetrate down into the gaps between the boxes, forming a waffle pattern of beams below and connected to the concrete slab. These beams made the concrete slab stronger, and reduced the total amount of concrete needed, compared with a simple thicker slab of equivalent strength.
The infringement action
Baygol sued Huntsman Chemicals* and Foamex for contributory infringement of its patent, in separate actions before the Federal Court of Australia. Each of those companies supplied polystyrene boxes which Baygol said would be used by builders to infringe its patent. As part of their defence, each of the respondents said that there could be no infringement because builders did not use concrete spacers in making the reinforced concrete slabs, they used spacers made of plastic.
Justice Tamberlin agreed to decide, as a preliminary question, whether the words ‘concrete spacers’ in claim 1 could encompass spacers made of plastic. In effect, he was deciding whether the word ‘concrete’ could be simply ignored.
The court’s decision
Baygol argued that because plastic spacers worked in the same way as concrete spacers, and because this would have been apparent to those working in the industry at the relevant time, the patent claim should be construed expansively so as to encompass the use of plastic spacers in its patented method. It argued that all of the benefits of its invention were still being enjoyed by such a use.
Justice Tamberlin reviewed a series of decisions which said that the emphasis must be on the language of the claims as chosen by the patentee, and he concluded that there was nothing in the patent claim or specification that could justify doing ‘such violence to the language of the claim or ignoring the language chosen’ such as to permit a claim construction that ‘concrete’ could include ‘plastic’ in its meaning.
In reaching this conclusion Justice Tamberlin provides a welcome reminder that a patentee should choose its claim language carefully since usually the words chosen should bear their ordinary meaning. This both protects the public who look to the claims to tell them what monopoly the patentee has staked out, and protects patentees who will often carefully choose their claim language so as to avoid potentially dangerous prior art disclosures.
*Freehills acted for Huntsman Chemicals in this proceeding.
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