Part 1: Prior Art

This themed series of articles will answer some common questions encountered in patent law. The series commences with a discussion on prior art.

What is prior art?

A simplistic definition of "prior art" is any publicly available information that exists at any time before the date on which a patent application is filed for an invention.1 Australian law has held that information is publicly available if the material can be inspected "as of right" by the public. There is no age limit on prior art - a relic that is thousands of years old may still be considered prior art.

Prior art not only includes information made public in Australia but also information made public worldwide. For example, a book that is able to be borrowed from a library in Mongolia may be considered prior art for a later-filed Australian patent application.

Prior art typically sets the background or framework for an invention but may also be an obstacle to obtaining a valid patent.

What is the importance of prior art?

A patent may be granted for an invention which is, amongst other things, novel (i.e. new) and inventive (i.e. not obvious). The assessment of whether an invention is new and not obvious is undertaken with reference to prior art.

As such, prior art plays a critical role in determining whether an invention is patentable (i.e. whether a valid patent may be granted for an invention) or if an existing patent is valid.

What happens if prior art is found against a patent application?

During examination of a patent application, patent examiners will often find one or more prior art documents which may be relevant to the invention disclosed in the application. The patent examiner may argue that the invention is not patentable because a prior art document has previously described or shown the invention to the public, thereby rendering the invention not new or obvious.

As patent attorneys, we typically look for differences between the prior art and the invention, however subtle they may be. We work with these differences to either amend the patent application to more clearly define the invention or present arguments to the examiner explaining why the invention is new and inventive in view of the prior art.

What may be considered as prior art?

There are several forms or types of prior art which may be recognised depending on the jurisdiction. Typically, prior art may be categorised either as information in a publicly available document or information made publicly available through doing an act.2

Some examples of documents recognised in Australia as prior art include:

  • Patent publications (including patent applications and patents which may or may not be active)
  • Books
  • Journal articles
  • Magazines
  • Brochures
  • Comics3
  • Photographs
  • Websites and webpages (including videos on YouTube)
  • Posters
  • Sound recordings and CDs
  • Computer data-banks

Certain acts may also be considered as prior art:

  • Oral disclosures (such as at trade shows, conference events, seminars, demonstrations or the like)
  • A sale of or an offer to sell a product which embodies the invention
  • Commercial use of the invention

In light of the above, it is imperative to keep the invention confidential and not commercially use the invention prior to seeking patent protection.

What is not considered as prior art?

It follows from the definition of prior art that information which is not publicly available prior to filing of the patent application generally cannot be considered as prior art.4

Accordingly, any information which is confidential in nature cannot be used as prior art, even if it occurs prior to filing the patent application. A typical example of this are trade secrets. Another example is where a disclosure has been made in a provisional patent application and no further associated patent application(s) have been filed. This is because the contents of a provisional patent application are not published and remain secret. 

There may be instances where disclosing an invention to third parties prior to seeking patent protection is unavoidable. In such instances, it is strongly advisable to have in place a suitably drafted and specific non-disclosure agreement (NDA) or confidentiality agreement to ensure such disclosure is made in confidence.

A word of caution: commercial use of an invention even if in secret or in a confidential manner may potentially invalidate a later-filed patent application. The rationale behind prohibiting the patenting of an invention that has been secretly used is that the patentee would enjoy an extended monopoly beyond the maximum legislated term of a patent.5 Notably, use of an invention in the context of reasonable trial or experiments is generally exempt from being considered as secret use.

What are the benefits of a prior art search?

A professionally performed search for prior art may provide several commercial and strategic benefits. The quality and extensiveness of a professional search is largely proportional to the budget outlaid. If the value of patent protection for an invention is high, it may be worthwhile investing a reasonable amount of time and money into a quality prior art search.

One form of prior art search is a patentability search which may be conducted prior to filing a patent application or following grant of a patent.

If conducted pre-filing, a patentability search seeks to uncover prior art which may be an obstacle to obtaining a valid patent for an invention. The search may assist with determining if the invention is unique and if pursuing patent protection is worthwhile.

If conducted following grant of a patent, a patentability (or validity) search seeks to uncover prior art which may be relevant to the novelty and inventiveness of an invention as claimed in a granted patent. The search may be performed prior to either commercialising the patent (such as licensing) or commencing an enforcement action (such as infringement proceedings) to effectively provide an indication of the 'strength' of the patent.

Another useful search to consider is a freedom-to-operate or infringement search (which may be a separate topic for discussion entirely). Briefly, an infringement search may be conducted prior to developing or launching a product to market to analyse and mitigate the risk of infringing existing patents. The search will typically be limited to finding active or in-force patents in jurisdictions in which the product will be commercially exploited.

Prior art searches may be complex and highly technical. It is strongly recommended to seek advice and assistance from a qualified patent attorney before undertaking such searches.


If we can be of assistance or should you have any questions regarding the above, please do not hesitate to contact us.


1 The date referred to is the "priority date" which is the date on which a first patent application is filed in respect of the invention. In a family of patent applications, each application may share the same priority date.

2 In Australia, there is another category of prior art referred to as a "Whole of Contents" documents which is information contained in certain Australian patent specifications that have been published on or after the priority date/filing date of the patent application. Such "Whole of Contents" documents are only relevant for the purposes of assessing novelty (i.e. newness) and not inventiveness (i.e. obviousness) of the invention.

3 A Donald Duck comic was used as prior art to reject a Dutch patent application.

4 See exception in footnote 2 referring to a "Whole of Contents" document.

5 In Australia, a standard patent has a maximum term of protection of 20 years from the date of the patent. This term may be extended in certain circumstances for subject matter relating to 'pharmaceutical substances'.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.