On March 17 the Full Federal Court in Melbourne refused an appeal by Japanese food seasonings maker Ajinomoto against the invalidation of its patent by the full court in 2006.

“There’s a bit in this decision for everyone,” Wayne McMaster, a partner of Mallesons Stephen Jaques in Melbourne, told Managing IP. “It restricts where relevant art should be, but it says that the document, when you are looking at it, doesn’t have to be in the exact area which is the subject of invention.”

Ajinomoto was granted a patent with a priority date of March 10 1997 for a blend of sweetners. Nutrasweet, the maker of sugar substitute aspartame, opposed the patent for a number of reasons, including lack of inventive step and cited a 1993 French patent. At first instance the judge held that the 1993 patent invalidated the Ajinomoto patent. Ajinomoto appealed to the Full Court.

The Full Court carefully considered section 7(3) of Australia’s Patent Act, which allows additional documents to be added to the common general knowledge to assess whether an invention is obvious.

At the time when Ajinomoto filed the patent, section 7(3) stated that the prior art that could be used to invalidate an invention must be information that the skilled person could “be reasonably expected to have ascertained, understood and regarded as relevant to work in the relevant art in the patent area".

Ajinomoto argued that this refers to work that has been carried out in Australia and the judges agreed. However, Section 7(3) was altered in 2001, so this part of the decision is only relevant for patents filed after the Patent Act was amended in 1990 and before April 1 2002.

The Full Court still found the patent invalid, stating that it was “concerned with the blending of known sweetners” and that there was work in the relevant art in Australia at the priority date.

Although the restriction of prior art to Australia could be interpreted as making patent invalidation more difficult, the Full Court also said that evidence of work in Australia does not need to be in the exact area which is the subject of invention.

The Full Court also did not accept Ajinomoto’s argument that section 7(3) states that a document used as prior art should “stand out from the crowd” in order to be relevant.

Ajinomoto has not yet said whether it intends to appeal to the High Court.

Griffith Hack acted for Ajinomoto and Allens Arthur Robinson represented NutraSweet Australia in the case.