The importance of a carefully drafted provisional patent specification

The importance of a carefully drafted provisional specification can often be neglected. For example, it is not uncommon for a potential patent applicant to be tempted to have a provisional specification prepared on a low budget. For at this early stage funding can be tight, and there can also be a high level of uncertainty about the likelihood of commercial success of the technology and the commercialisation path that is selected to seek that success.


It is also possible that a provisional patent specification may be prepared within a restricted timeframe to quickly secure an early filing date for the invention.

Accordingly, it can happen that the provisional patent specification that is ultimately filed contains less detail or less finessing than would have been the case if a higher budget or a less restricted timeframe had been available. On the other hand, the case may simply be that the finer details of the invention were unknown at the time the provisional patent application was filed.

Australian provisional patent applications are generally filed to secure an early filing date for the subject matter contained within the accompanying provisional patent specification. A complete patent application is then filed within the preceding twelve months which is accompanied by a complete patent specification that includes all the subject matter of the provisional patent specification and perhaps additional details due to advancements or refinements that have occurred to the technology since the filing the of provisional patent application. Provided the complete application is filed within twelve months of the filing date of the provisional application, the complete application may be entitled to the priority date of the earlier filed provisional application.

However, applicants should bear in mind that, in some circumstances, one or more claims ultimately granted in respect of a complete application may not be entitled to the earlier priority date of the provisional application.

Priority dates

The priority date of a particular claim in a specification is the earliest of: the date of filing the specification; or if the claim is fairly based on matter disclosed in one or more priority documents, the date of filing the priority document in which the matter was first disclosed. Accordingly, if a claim of a complete application includes matter which was not originally disclosed in the provisional specification from which it claims priority, the claim will not be entitled to the earlier priority date. In this case, the priority date of the claim would be the filing date of the complete application.

For example, the recent Federal Court of Australia decision of Bradken Resources Pty Ltd v Lynx Engineering Consultants Pty Ltd acts as a reminder of the importance of carefully drafting a provisional specification so that it includes as much detail as possible.

In the above decision of, it was found that the claims in the granted patent included a feature for which there was no written disclosure in the earlier filed provisional specification. Accordingly, the priority date of the claims was determined by the Court to be the filing date of the complete specification, not the filing date of the provisional specification. This finding resulted in a need to defend “secret use” allegations due to the patent applicant’s activity between the filing dates of the provisional and complete applications.

Conclusion and practical advice

The above decision of the Federal Court emphasises the general principle that it is important for a provisional specification to be drafted with the same care that would be applied to the drafting of a complete patent specification so that the description of the invention is as detailed as possible. That is, each aspect of the invention, despite its perceived importance, should be described in as much detail as possible. This is because one or more aspects which were not initially considered as important may later be discovered to be vital to the invention as claimed in the ultimately granted patent. The objective should be that basis for any amendments to the claims of the invention which may be required can be found in the initial disclosure so that the risk of losing a priority claim to an earlier filed patent specification is reduced.

The decision is also a reminder for potential applicants to avoid the real and alluring temptation of trying to cut corners in the earlier phases of the patent process.

It is appreciated that it may not always be possible for a detailed provisional specification to be prepared in the first instance. If you do find yourself in this less than ideal situation there are other risk management steps that can be implemented such as:

  • Having good confidentiality agreements in place with external parties
  • Limiting the disclosure and use of the invention until a detailed provisional application has been filed
  • Closely monitoring your continuing research and development activities for:
    • aspects of the invention which are revealed to be important which were not fully described in the initial provisional specification and
    • improvements made during development of the invention

so that a supplementary patent application or applications can be filed for those aspects or improvements. The above steps are useful in all circumstances, but become even more important in the circumstances being considered in this article.

All inventions are different, and all commercialisation paths are unique. Accordingly, whilst the commentary provided above should prove useful in identifying the underlying principles, it is no substitute for specific advice from a patent attorney in respect of your own circumstances. For there always remains the need to reach the optimum balance between risk and return, and that has to be assessed on a case-by-case basis.