A patent is a legal contract between the owner of an invention and the state. The contract requires full disclosure of the invention by the owner, in exchange for which the owner is granted the exclusive right to prevent others from using the invention for a fixed term. In some jurisdictions, a general disclosure of the invention should also be accompanied by a disclosure of any non-essential but preferred or advantageous features of the invention, the so-called best mode.
To illustrate the purpose of the best mode requirement, imagine a patent directed at a method for making a novel and inventive cheesecake that is more delicious than any previously known cheesecake. The claims specify a method for making a cheesecake using soft Italian cheese. The description provides examples of the claimed method using the soft Italian cheeses ricotta and mascarpone, and thereby allows a skilled person to perform the invention. However, in the inventor’s cheesecake factory, the cheesecake is made using the soft Italian cheese mozzarella, because the inventor knows that mozzarella produces a cheesecake that is even more delicious than cheesecake made with either ricotta or mascarpone. The benefits of mozzarella were known to the inventor at the time the application for the patent was filed, but were not disclosed. The inventor thereby retains an advantage over her competitors when the patent expires, and benefits from two forms of IP protection for their invention: a patent for making a cheesecake with soft Italian cheese and the trade secret of using mozzarella as the soft Italian cheese.
The best mode requirement is, of course, most relevant to the fields of life sciences and pharmaceuticals, in which an inventive product or process is influenced by an array of different factors. Importantly, the best mode is not necessarily the best way of performing the invention, but is merely what the applicant believes to be the best way of performing the invention.
The US, Australia and New Zealand all possess a best mode requirement, whereas the UK, Europe, China, Canada, Korea and Japan do not have best mode provisions.
Best mode in the US
Prior to the change in US law in 2011 (pre-AIA), insufficient disclosure of the best mode was grounds for rejecting a patent application during prosecution and for invalidating a granted patent. Insufficient disclosure of the best mode represented an important potential defence in patent infringement proceedings, particularly in cases where there was a discrepancy between the examples provided in the patent and the commercial embodiments of the invention sold by the patent proprietor.
Under current US law (AIA), the best mode requirement still applies during prosecution. However, insufficient disclosure of the best mode is no longer grounds for invalidating a granted patent. During prosecution, a US Examiner will typically assume that a specification discloses the best mode unless there is clear evidence to the contrary.
Best mode in Australia
In Australia, insufficient disclosure of the best mode can be grounds for rejecting an application during prosecution and for invalidating a granted patent. Contrary to the direction of travel in other jurisdictions, for which the importance of best mode has diminished, two recent cases have established the importance of the best mode requirement in Australia.
In March 2017, the Australian Federal Court revoked a patent for failing to disclose the best mode of the invention. The patent at issue (Australian Patent No. 2003200700) was directed towards a new perindopril salt having greater stability than previous formulations of perindopril. The specification of the patent stated that the salt could be prepared “according to a classical method” of making salts. However, the proprietor (Servier) was aware at the time of filing that the salt had been made according to specific methods not mentioned in the specification. The Federal Court found that, because the use of these specific methods produced a better and more stable salt than salts produced by the classical method, the best mode requirement had not been satisfied on filing and that the patent was therefore invalid. This was despite the fact that the claims themselves were directed to the perindopril salt and not the method for making the salt. A key part of the court’s reasoning for finding a lack of best mode disclosure was that using the undisclosed method produced a more stable salt than using the classical methods, such that the undisclosed best mode was relevant to the inventive concept of the claim.
In August 2017, the Australian patent office rejected an application for failing to disclose the best mode. Claim 1 of the application was directed to compounds for treating viral infections. The description did not provide details on how to make the compounds. The applicant (Kineta) had in fact purchased the compounds from a supplier and did not know how the compounds were made. The Australian patent office rejected the application for failing to disclose the best mode of obtaining the compounds, and indicated that a statement to the effect that the compounds could be purchased from the known supplier, would have satisfied the best mode requirement. However, the patent office also ruled that amending the application to include such a statement after the filing date could not be accepted, as it would add subject matter to the application as filed.
Defence to a best mode objection?
In both the US and Australia, a best mode objection cannot be overcome by adding subject matter to the application or patent that was not disclosed on the filing date. Therefore, to overcome a best mode objection, applicants and proprietors are often required to demonstrate that the best mode is implicitly disclosed by the specification, i.e. that it would be obvious to a skilled person in view of their common general knowledge. Such an argument has more chance of succeeding if the best mode under discussion is not directly related to the inventive aspect of the claimed product or method.
Historically, the best mode requirement has been considered an important peculiarity of US practice. However, by removing best mode requirement as a ground for invalidating a patent, AIA reduced the importance of best mode in the US. By contrast, recent Australian case law has established best mode as an important requirement in Australia during prosecution and post-grant. An understanding of the best mode requirement therefore remains important for applicants seeking international protection for their inventions.
This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.