Keeping the problem to be overcome in mind, identify the person skilled in the art (PSA); that is, the skilled person. This is the person to whom the specification is addressed and through whose eyes the specification is to be interpreted.

The PSA is generally considered to be:

familiar with the state of the art at the relevant time; and
typically, a skilled but non-inventive worker in the relevant field of technology.

Note that the PSA is not a specific person but an artificial construct.

Identifying the skilled person

The skilled person is the person to whom the specification is addressed and through whose eyes it is to be interpreted (see Root Quality Pty Ltd v Root Control Technologies Pty Ltd (2000) FCA 980 at paragraph 70).

This person is acquainted with the surrounding circumstances of the state of the art and manufacture at the relevant time (the priority date of the application). They are likely to have a practical interest in the subject matter of the invention and may often work in the art with which the invention is connected (see KD Kanopy Australasia Pty Ltd v Insta Image Pty Ltd (2000) FCA 481).

The PSA is a skilled but non-inventive worker in the relevant field of technology. Their characteristics are those of the notional worker in the relevant field:

their qualifications;
their degree of experience;
the practices they regard as commonplace;
the setting in which they operate; and
the resources with which they operate.

(Aktiebolaget Hassle v Alphapharm Pty Ltd (2002) HCA 59 at paragraphs 151 - 153).

These characteristics are determined in the context of the field of knowledge to which the invention relates.

Multiple addressees

However, the person skilled in the art is not a real person but an artificial construct that is used as a tool of analysis which is used to make the determination (see AstraZeneca AB v Apotex Pty Ltd (2015) HCA 30 at paragraph 23.

They may be a ‘composite being’ (that is, skilled in more than one art) or a team of people (for example a team of mechanics and chemists) (General Tire & Rubber Co. Ltd v Firestone Tyre & Rubber Co. Ltd (1972) RPC 457 at page 482; Osram Lamp Works Ltd v Pope’s Electric Lamp Co. Ltd (1917) 34 RPC 369 at page 391).

The Examiner as Addressee

In taking the position of the PSA, examiners are not expected to be fully familiar with the language of every art. If the examiner has raised an objection of lack of clarity of some terms used in the specification, and the applicant has responded that such terms are perfectly clear to the addressee (the PSA), we should not maintain the objection if the terms are used in relation to inconsequential features.

However, where the terms are material to understanding the invention or its scope, we do not necessarily accept a mere assertion that the terms have a clear and unambiguous meaning to people other than the examiner. We may require corroboration if such an assertion is made by a person who has not established that they are skilled in the art – for example, the applicant’s attorney. Similarly, assertions may be questioned when they are made by one person under instructions from another.

Sometimes, the applicant will supply or cite corroborating material such as references in dictionaries or handbooks, or examples of usage in the trade. If there appears to be conflict between sources, the terminology used by the applicant should be reinforced by a reference to the relevant source which establishes the required meaning.

Evidentiary Requirements

In the decision of Commissioner of Patents v Emperor Sports Pty Ltd [2006] FCAFC 26; 67 IPR 488, the requirement for evidentiary proof as to the nature and knowledge of the person skilled in the art was considered:

“In considering who is the appropriate skilled person, and what such person might be reasonably expected to do when faced with the problem in hand, sometimes, indeed often, evidence may not be necessary. In many instances the answers will be obvious to the parties, the Commissioner and the court. In high technology areas for example it will usually be assumed that the relevant skilled person will be familiar with the major professional or academic journals and could reasonably be expected to consult them. No evidence is required.”

In situations where there may be doubt or disagreement, it was noted that:

“…it is necessary to have either evidence or, which amounts to the same thing, reliance by an administrative decision-maker of expertise appropriate to the office.”

and furthermore:

“The Commissioner is an administrative decision-maker equipped with technical expertise. ….. he or she is entitled to make use of that expertise, and draw inferences that may be rationally drawn from technical knowledge, including how skilled persons of various descriptions may act in their respective occupations ….”

In these circumstances, the knowledge of the Commissioner is prima facie to be relied upon by the Office as evidence as to what the person skilled in the art would do.

Relevant Case Law

Below are relevant case law surrounding principles of determining the PSA.

A patent specification is addressed to a person skilled in the relevant art of the specification. This person brings their understanding of the terminology and workings of the art to the construction of the specification. Lord Shaw in B.T.H. v Corona Lamps 39 RPC 49 stated:

"A specification must take its rank among all ordinary documents which are submitted to a reader for his guidance or instruction, and a reader ordinarily intelligent and versed in the subject matter. Such a reader must be supposed to bring his stock of intelligence and knowledge to bear upon the document, not unduly to struggle with it, but anyhow to make the best of it."

Thus, the specification is to be construed in the light of the common general knowledge in the relevant art at the priority date of the application. As stated in Welch Perrin v Worrel (1961-62) 106 CLR 588 at 610:

"If it is impossible to ascertain what the invention is from a fair reading of the specification as a whole, that, of course, is an end of the matter. But this objection is not established by reading the specification in the abstract. It must be construed in the light of the common general knowledge in the art before the priority date."

See also Decor Corp v Dart Industries 13 IPR 385 and Melbourne v Terry Fluid Controls Pty Ltd (1994) AIPC 91-058

A full discussion of a number of relevant decisions on this subject is given in Valensi & Another v British Radio Corporation (1973) RPC 337. In particular, at page 377:

"We think that the effect of these cases as a whole is to show that the hypothetical addressee is not a person of exceptional skill and knowledge, that he is not expected to exercise any invention nor any prolonged research inquiry or experiment. He must, however, be prepared to display a reasonable degree of skill and common knowledge of the art in working trials and to correct obvious errors in the specification if a means of correcting them can readily be found."

The Valensi case (supra) should be read in the light of the observation in American Cyanamid Company v Ethicon Limited [1979] RPC 215 at page 245, to the effect that:

"... many of those involved and taking part in the placing on the market of such a new product, which was artificial and had no previous equivalent in this respect, would be highly qualified scientists trained at least to university standard, with all that entails, and used to carrying out chemical and biological research work in research departments. That is what in fact happened in the case of both the plaintiffs' and the defendants' artificial sutures here, and it would ... be highly misleading to suggest that there was in fact, in the present case, any body of 'intermediately' skilled technicians to whom the specification could be addressed whose existence must be assumed to be 'obvious', as was assumed by the Court of Appeal in the Valensi case (1973) RPC 337. The correct view ... which is consistent with the principle which the Court of Appeal must ... be presumed to have acted upon, is to hold as matter of law ... that the answer to the question: "Who is the skilled addressee of the specification?", depends upon making an examination of the facts of each case, and in so doing regard must be paid primarily to the nature of the invention, to the nature and size of the industry concerned, and the way it is organised for the purposes of conducting research into and of producing and marketing its products."

The position in Australia is no different from that in the UK. In Universal Oil Products v Monsanto (1972) 46 ALJR 658 Gibbs J. stated:

"The specification is sufficient if the patentee makes the nature of his invention, and how to perform it, clear and intelligible to persons having a reasonably competent knowledge of what was known before on the subject to which the patent relates, and having reasonably competent skill in the practical mode of doing what was then known."

Amended Reasons

Amended Reason	Date Amended
	18 Oct 2023
Published for testing	06 Jun 2023

5.5.2.2 The Addressee

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