Ever since its introduction into the 1952 Patents Act, there has been a statutory requirement for an Australian complete patent specification to include a disclosure of the ‘best method known to the applicant of performing the invention’.

Although the failure to include the best method has long been a ground upon which a patent could be held invalid, attacks against patents for lack of best method have been relatively rare. As a consequence, the issue of what the best method requirement means in practice, and how that requirement can be met, has been the subject of limited attention in the Australian courts.

However, in the recent Full Federal Court decision of Servier v Apotex1, the Full Federal Court upheld the trial Judge’s decision revoking a patent for failure to provide the best method. In so doing, the Full Court looked in some detail at the best method requirement.

The Full Court made it clear that, in looking at the question of the best method, the critical consideration is to understand the nature of the invention, not simply at what was claimed.

The facts

The patentee was Servier, and its patent related  to a chemical compound perindopril, used for  the treatment of heart disease. Perindopril and its pharmaceutical qualities were previously known, having been the subject of an earlier patent. However, there were problems with finding a pharmaceutically acceptable salt of perindopril which had good bio-availability and adequate stability needed for the preparation and storage  of pharmaceutical compositions.

The solution presented in the Servier patent   was the arginine salt. The only information as to the preparation of the arginine salt contained in the specification was that it had been ‘prepared according to a classical method of salification of organic chemistry,’ (salification simply means to form into a salt). Servier knew before it filed its patent application that perindopril arginine had been prepared in 1986 and 1999 (well before  the priority date of the patent), using two slightly different classical salification methods. Neither method was referred to in the specification.

At first instance, the trial Judge held that there had been a failure to provide the best method. On appeal, the Full Court agreed.

Issues on the appeal

Although there were a number of arguments made by Servier in the appeal, probably the most interesting was that the best method requirement is met by identifying the essential integers of the product. Servier argued that as the relevant claims were to a product and not a process, the best method obligation was met by identifying the claimed compound and details of the method of producing it were not required.

This was rejected by the Full Court. The Full Court said that the key to understanding the  best method obligation was to understand that   it was directed to the method of performance ‘of the invention’. The nature of the invention is as described by the whole of the specification.

In this case, the trial Judge had recognised that the ’point’ of the invention was the storage ability of a compound. That storage ability can vary depending on the nature of the salt formed and can vary with the form of the salt. Accordingly, the particular salt formation and the methodology to get that salt formation, have more importance than might be the case where the claimed invention was a product for which those characteristics were irrelevant. Further, ‘the patentee has an obligation to include aspects of the method of manufacture that are material to the advantages it is claimed the invention brings’.

The claimed class of compounds were described as a patentable invention in the specification because of their properties, including their  use as pharmaceutical compositions. In those circumstances, there was an obligation on  the patentee to provide the best method for producing a form of perindopril arginine that would best fulfil the promises of the invention.

The trial Judge had held that Servier had failed to describe the best method known to it in performing the invention where it described only the general method of salification rather than  any specific method. Such specific methods include the 1986 or 1991 methods which would have provided the reader with information as to a method that met the characteristics of the claimed invention. The Full Court held that Servier had not shown that the trial Judge was wrong.