Re-patenting the prior art – how to avoid “reinventing the wheel”!


It is, unfortunately, a relatively common occurrence to find patent applications filed in which the inventor has discovered some unique characteristic or property of, say, a “new” composition they have prepared, and which they believe is worthy of patent protection, only to later find that the purported invention is not novel or inventive. In particular, experiments are undertaken which yield surprising, unforeseen, or counterintuitive results to the inventor, who then prepares and files a patent application with much enthusiasm, only to later find that the invention is new and surprising to them, and that another researcher has traversed the same research path and already published the invention. To avoid this situation occurring, it is obviously preferable to conduct a reasonably thorough assessment of the prior art before embarking on new research.

In the following, we set out some other matters to be aware of to avoid preparing and filing patent applications that might potentially attempt to re-patent the prior art, thereby wasting significant time, effort, and resources.

An implicit disclosure in the prior art?

The test for novelty in Australia is the “reverse infringement test”, which asks the question “whether the [prior art] would, if the [claims of the] patent were valid, constitute an infringement [of those claims].”[1] Put simply, if the prior art has “each and every one of the essential integers”[2] of a claim, then the claim lacks novelty. To assess whether a prior art reference discloses each of the essential features of a claimed invention, it must “be interpreted as at the date of its publication, having regard to the relevant surrounding circumstances which then existed, and without regard to subsequent events.”[3] In other words, the prior art reference must be read and interpreted though the eyes of the person skilled in the art (PSA) and using the common general knowledge (CGK) in the art at the date of publication. The relevant question to be considered is how the prior document would strike an instructed reader, and not what was in the mind of the author.[4] 

What happens, however, if the prior art document does not explicitly disclose every essential feature of a claim? 

It is impermissible to simply add or “fuse”[5] CGK to a prior art document to establish lack of novelty.  However, if the prior art document discloses some but not all the features of a claim, the claim is not novel if the PSA “would add the missing information as a matter of course and without the application of inventive ingenuity or undue experimentation.”[6] In other words, a claim is not novel if the prior publication does not specify an integer “but the skilled reader would understand that integer to be present in the subject matter described.”[7] 

A simple example of this might be if one of the steps in the claims is to react a mixture of components A and B “in a reaction vessel”, and the prior art document describes the same reaction but does not specify the use of a reaction vessel. It seems likely that the PSA would understand that a reaction vessel must have been used in the prior art to conduct the reaction of A and B, even though it is not explicitly described.

Alternatively, it is sometimes the case that that the author of the prior art document and the “new” inventor have approached the same invention from different starting points, and it may for this, or for other reasons that the inventions have been described differently (by the prior art author and the new inventor) such that it cannot be immediately discerned from a reading of the language which they have respectively used that they have, in truth, discovered the same invention. Case law provides for this situation as follows: “if carrying out the directions contained in the prior inventor’s publication will inevitably result in something being made or done which [has each and every one of the essential integers of a claim, then] … this circumstance demonstrates that the patentee’s claim has in fact been anticipated.”[8] In other words, the prior art need not explicitly disclose all of the essential features of the claimed invention, and a novelty-destroying disclosure may instead be implicit[9]. A missing feature may be: a.) inferable from information provided by the prior publication, b.) inherent property of an already existing product, or c.) an inevitable or inexorable result of following the directions provided in the prior art.[10]

A simple example of this might be if the claims are directed to a composite material that has a certain property (e.g., a hardness value) and the prior art document describes a heat treatment process that has been used on that composite. If following the instructions of the prior art on the composite would, as a result of that heat treatment process, have a hardness value falling within the scope of the claims, then the claims are not novel. Simply quantifying a property or evaluating a new parameter is not sufficient to confer novelty (also see below in relation to “parameteritis”).

In summary, if the prior publication does not explicitly state an integer but the skilled reader would understand that integer to be present, or if it is an inevitable or inexorable result of following the directions provided in the prior art that the feature is present, then a claim to that combination of features plus the “missing” integer will not be novel.

Is a mosaic of prior art relevant?

Some further complexity can arise where the prior art can be mosaiced. Australia’s patent laws provide that prior art information made publicly available in 2 or more related documents[11] (or through doing 2 or more related acts), can be used if the relationship between the documents (or acts) is such that a PSA would treat them as a “single source of that information”.[12]

What constitutes a single source of information is highly dependent on the circumstances, including the nature of the field of art, the nature of skilled addressee, and of course the degree of connection which is stated to exist in the documents themselves.[13]  Whilst it is generally rare to establish that a claim lacks novelty in view of a mosaic of prior art documents, the point to note here is that, in some cases, it is not enough to confine an assessment of the prior art to a single prior art document. There is also inventive step to consider in terms of a mosaic, but this is beyond the scope of this article.

Is mere optimisation of a prior art system enough?

In some cases, the prior art describes a system (such as a composition) that has a number of “input” parameters that have ranges of values.  Inventors can carefully balance those input parameters to produce an optimised output, and file a patent application to that optimised composition. The question is whether claims to that optimised composition are patentable, or whether this is an attempt to re-patent the prior art.  

In terms of novelty, this somewhat akin to making a selection of the ranges of those input parameters. A selection patent is capable of being novel, provided certain criteria are met. For a selection to be patentable, the:

  1. selection must be based on some substantial advantage gained or some substantial disadvantage avoided;
  2. the whole of the selected members must possess the advantage in question; and
  3. the selection must be in respect of a quality of a special character which may fairly be said to be peculiar to the selected group.[14]

Whenever a range is specified, it is likely that some values will have better results than others. However, it has been held that finding the optimum values, which constitutes a mere choice between alternatives, does not constitute a selection – a selection has the quality of being “unexpected”.[15]

Another possibility that is encountered is where there are known guidelines or “rules of thumb” on the resulting stability of a system in response to varying those input parameters. Such guidelines tend to be matters known by the researcher and applied during their day-to-day work in the particular field of art, and therefore these tend to be considered as part of an investigation into inventive step. However, there may be debate on whether or not such guidelines form part of the CGK, whether they are any more than just a rough guide (i.e., a question of reliability), and they might not be consistently known, or even consistently applied by the PSA. In many cases, these guidelines are held “in-house”. Assuming, however, these guidelines are well known and understood by the PSA, there would seem to be a strong argument that such guidelines render claims which define an optimised system, obvious. However, it has been recognised in case law that “the fact that a general rule is prevalent does not make a further precise rule involving identification of precise parameters underlying the general rule a superfluous exercise not involving innovative merit.”[16]

In summary, to avoid re-patenting the prior art, an optimised system must be shown to satisfy the selection criteria set out above, and/or must generally have the quality of being “unexpected”.

New parameters, but is the invention new?

In some cases, it sometimes transpires that a researcher gains access to new test equipment which did not exist at the time of the prior art, and generates a series of new parameters from those tests relating to a new product or feature of a new process. A search of the prior art does not reveal those same parameters, and patent claims are then pursued which are limited by reference to that series of parameters. This style of claiming is referred to as “parameteritis” or “parametritis”.[17]

The attraction of this approach is obviously that is it may be impossible to prove now that the prior art inevitably exhibited the parameters. The question then becomes whether the parameters are essentially arbitrary, or whether they have some technical effect.[18]  If there is evidence which supports the fact that the parameters have been carefully chosen, are part of the invention, and are related to a claimed advantage, then the claims are likely to be novel.

A simple example of this might be where the claims under consideration limit the ranges of constituent components of, say, a metal alloy in an arbitrary way, and where the specification does not suggest that those limitations form part of the invention.[19]  In such a case, the claims would not be considered novel. Conversely, if the parameters have been carefully chosen, are part of the invention, and are related to a claimed advantage as part of the combination of the design, then the claims are likely to be found to be novel.


Finally, some researchers are well aware of these issues, and file patent applications anyway with an understanding that there is some inherent risk in the application (i.e., a so-called “speculative” application), meaning the applicant is gambling on being able to mine from the reservoir that is the patent specification some features that are novel, and assemble an argument (usually during prosecution, and potentially with accompanying post-filing data) that those combined features are inventive. This is essentially predicated on the understanding that one should be able to patent up to the limit of the prior art (i.e., what is novel) and what is not obvious in view of the prior art (i.e., what is inventive). Even if the protection is narrow this approach might still be commercially useful, especially in a crowded field of art. Under these circumstances, drafting the patent specification is even more important than usual as it needs to comprehensively provide for fall-back positions so there is support for amendments to navigate around the prior art during prosecution.  An abundance of examples can also improve the prospects of constructing a commercially useful fallback position.

Given these complexities, the involvement of an IP professional is essential, and in particular it is worthwhile speaking to an experienced patent attorney at an early stage of the process to seek advice on the inventive concept, and how the invention may be claimed in view of the prior art.

Spruson & Ferguson attorneys are highly experienced in helping businesses navigate these complexities.

[1] as set out in Meyers Taylor Pty Ltd v Vicarr Industries Ltd (1977) CLR 228 at page 235 (Meyers)

[2] Rodi and Wienenberger AG v Henry Showell Ltd, (1969) RPC 367 at 391

[3] General Tire & Rubber Co v Firestone Tyre & Rubber Co Ltd [1972] RPC 457 (General Tire)

[4] Bloch and Ilford Ld’s Patent (1936) 53 RPC 92 at page 98, lines 14 to 16

[5] Zetco Pty Ltd v Austworld Commodities Pty Ltd (No 2) [2011] FCA 848 at [111] (Zetco)

[6] H Lundbeck A/S v Alphapharm Pty Ltd [2009] FCAFC 70; 177 FCR 151 (Lundbeck) at [173], [180]-[181]

[7] Zetco at [93]

[8] General Tire at pages 485-486

[9] Bristol-Myers Squibb Company v FH Faulding & Co Ltd [2000] FCA 316; 46 IPR 553 at 576

[10] Shell Internationale Research Maatschappij B.V. v ExxonMobil Research and Engineering Company [2014] APO 31

[11] other than for “whole of contents” prior art

[12] section 7(1)(b) of the Patents Act 1990

[13] Nicaro Holdings Pty Ltd v Martin Engineering Co 16 IPR 545 at page 570

[14] I.G. Farbenindustrie A.G.’s Patents (1930) 47 RPC 289 – at pages 322 to 323

[15] The Carlton Tyre Saving Co’s Application (1973) AOJP 1404

[16] Barokes Pty Ltd v Amcor Packaging (Australia) Pty Ltd [2005] APO 56 at [92]

[17] as discussed by Laddie J in Raychem Corp.’s Patents [1998] RPC 31

[18] Euroceltique S. A. [2009] APO 21 at [112],

[19] Williams Advanced Materials Inc v Target Technology Co LLC (2004) 63 IPR 645 at [48]

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