Legal Insights

Best method alone strikes down another patent

By Ben Miller, Stephen Rohl

• 08 April 2020 • 5 min read
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Partner Ben Miller and Senior Associate Stephen Rohl consider a recent decision of the Federal Court which provides a timely reminder of the rise in status of the Australian 'best method' requirement for validity of patents. While it appears possible to amend a patent specification later to include the best method, the court is unlikely to do so where there has been delay by the patentee, particularly where the patentee has been put on notice of the defect by prosecution of corresponding patents in other jurisdictions.

In Brief

  • The Australian 'best method' requirement for patents has risen in status in recent years.
  • Patentees should ensure that their patents and patent applications disclose the best method known to them as at the filing date of the complete specification.
  • Australian patents are liable to be revoked if they do not comply with the best method requirement.


Section 40(2) of the Patents Act 1990 (Cth) requires that a complete specification provide the "best method known to the applicant of performing the invention".

In Les Laboratoires Servier v Apotex Pty Ltd [2016] FCAFC 27 (Servier), a Full Court of the Federal Court of Australia found a patent directed to perindopril arginine, a drug used to treat hypertension, invalid solely on the ground of failure to disclose the best method known to Servier. The Full Court also declined to overturn the primary judge’s decision to refuse to allow amendment of the patent to include the best method known to Servier.

The most recent in a run of decisions following Servier, BlueScope Steel Limited v Dongkuk Steel Mill Co Ltd (No 2) [2019] FCA 2117 provides a timely reminder that Australian patents are liable to be revoked if they do not comply with the best method requirement. This requirement is now somewhat uniquely Australian, as there is no equivalent ground in the European Patent Convention and it is not a ground of revocation in the USA.

Best method

BlueScope’s two patents in suit related to alloy-coated steel strip products useful, for example, as roofing or fencing material and methods for forming such products. The inventors of the patents found that controlling short range variations in the thickness of the alloy coating helped to minimise defects in the coating. One of the patents (the ‘257 Patent’) disclosed that this could be done by applying ‘special operational measures’ in the coating process, without providing any details of those measures. The other patent (the ‘258 Patent’) was silent in relation to how the variations were controlled but nonetheless emphasised the importance of doing so.

BlueScope conceded that, by the filing date, it knew of a combination of four operating measures to control thickness variations but contended that these would have been known to the skilled addressee. Further, BlueScope contended that application of the invention to any particular production line would have involved routine experiments to ensure the coating thickness was being appropriately controlled.
Beach J provided the following guidance on the best method requirement:

  • The complete specification must disclose each essential element or feature of performing the invention, even if a skilled addressee would know or could readily ascertain that element.
  • The patentee does not need to disclose details of the method which would be well-known and understood by the skilled addressee, such as well-known analytical agents, commonly used methods, well-known terms of art or a description of machinery in standard use.
  • The best method requirement will be satisfied if the skilled addressee can arrive at the best method known to the patentee of performing the invention by some routine experimentation, but without ingenuity or undue experimentation.
  • If the skilled addressee is left to make a choice as to which analytical agent, commonly used method or machinery to use, or is left in doubt as to what a term means, the best method will not have been described if that choice or uncertainty affects the performance of that method.

The court found that BlueScope had failed to disclose in the 257 Patent the best method known to it because the skilled addressee would not understand what was meant by ‘special operational measures’ in the context of the specification. Further, even if these measures formed part of the common general knowledge, by reason of the use of the word ‘special’, the skilled addressee would not understand that those known measures were being referred to (whether generally or the particular four operating measures known by BlueScope). In any event, the court found that particular aspects of the best method did not form part of the common general knowledge.

For similar reasons, and despite the fact that it does not use the expression ‘special operational measures’, the court found that the the 258 Patent did not disclose the best method.

Amendment application

BlueScope sought to amend the 257 Patent to include the best method known to it. Interestingly, the court considered this to be theoretically possible, even after grant of the patent. However, the court refused to do so, including because:

  • BlueScope failed to provide full and frank disclosure of all relevant matters in support of its amendment application, including relating to objections raised in examination of a related US patent application.
  • BlueScope had unduly delayed in making its request, some 10 years after filing and 6 years since the first commercial use of the method, in circumstances where it was on notice of the need to explain the expression ‘special operational measures’ based on the prosecution of related patent applications in Australia and other jurisdictions.

Key lessons

Where a best method of performing the invention is known to the patentee, this should be disclosed in the complete specification. Where no method is disclosed, or reliance is placed on methods well-known in the art (such as the ‘classical method of salification’ in Servier), a patent may risk invalidation for failure to disclose the best method. Prevention by way of amendment is the best cure, and patentees should be prompt in doing so once they are exposed to facts from which it was, or reasonably ought to have been, apparent to them of the need to remedy the complete specification.

This article was published in Edition 1 of The Prescription.

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