Rio Tinto Alcan and Norsk Hydro in Patent Opposition Dispute

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The potential importance and impact of prior third party use of an invention, together with careful attention to patent specification drafting, have been highlighted in a recent Australian patent opposition between Rio Tinto Alcan International Ltd and Norsk Hydro ASA [2015] APO 40 (Norsk Hydro is the patent applicant).

In this Australian patent opposition decision, the full text of which is available here (, certain claims to an invention relating to the addition of manganese to AlMgSi alloys to improve their extrudability, have been found to lack novelty – on the one hand due to the prior production of an alloy that fell within the scope of the claim, and on the other hand on the basis of a single prior disclosure in a document (a paper published in a technical journal). In both instances, it was clear that the prior act and prior document related to a composition that was the same as that claimed in Norsk Hydro’s patent application and that a homogenisation step was undertaken or described. However, the claimed presence of “dispersoids” wasn’t immediately apparent on the face of either the act or the document.

In these circumstances it is appropriate to consider whether the dispersoids would have been present, even though they are not explicitly referred to, in the prior art act or document. The evidence established that dispersoids were an inevitable consequence of a person skilled in this technical art conducting the homogenisation step (already established as present) in forming the alloy. So, both the prior act and the document were said to disclose all the features of the claimed invention. Had Norsk Hydro undertaken appropriate searching of patent and technical literature they may have located at least the prior published document.

Positively for Norsk Hydro, it was determined that several of their claims did not lack novelty, due to these claims being limited to a specific composition that was not evident from either the prior art act or prior art document, or from specific conditions for the homogenisation step. This highlights the importance of ensuring that the patent application is drafted with sufficient detail to support claims to specific ‘subsets’ of broader claims. So, rather than simply having their patent application refused as a result of Rio Tinto Alcan’s opposition, Norsk Hydro are given the opportunity to amend their application to ensure all claims are limited with features not present in, or not being the inevitable consequence of, the prior art document or act.