The Person Skilled in the Art

1In determining the person skilled in the art, the court ‘has to assume the mantle of the normally skilled but unimaginative addressee in the art at the priority date and to impute to him what was, at that date, common general knowledge in the art in question.’ (Windsurfing International Inc v Tabur Marine (Great Britain) Ltd (1985) RPC 59, pp 73-74, per Oliver LJ.) The task of the court is detailed in Lubrizol Corpn v Esso Petroleum Co Ltd: ((1998) RPC 727, p 738.)

Patent specifications are intended to be read by persons skilled in the relevant art, but their construction is for the Court. Thus the court must adopt the mantle of the notional skilled addressee and determine, from the language used, what the notional skilled addressee would understand to be the ambit of the claim. To do that it is often necessary for the Court to be informed as to the meaning of technical words and phrases and what was, at the relevant time, the common general knowledge; the knowledge that the notional skilled man would have.

2In Bishwanath Prasad Radhey Shyam v Hindustan Metal Industries (1978) the Supreme Court set out as “Another test of whether a document is a publication which would negative existence of novelty or an ‘inventive step’” the question “Had the document been placed in the hands of a competent draftsman (or engineer as distinguished from a mere artisan), endowed with the common general knowledge at the ‘priority date’, who was faced with the problem solved by the patentee but without knowledge of the patented invention, would he have said, ’this gives me what I want ?’”, and, “To put it in another form”: “Was it for practical purposes obvious to a skilled worker, in the field concerned, in the state of knowledge existing at the date of the patent to be found in the literature then available to him, that he would or should make the invention the subject of the claim concerned ?” (para 25). It held that a patentable invention “must involve something which is outside the probable capacity of a craftsman” (para 22).

3In Cipla v F Hoffmann-La Roche (2015) the Division Bench held that “The features of a person skilled in the art are that of a person who practices in the field of endeavour, belongs to the same industry as the invention, possesses average knowledge and ability and is aware of what was common general knowledge at the relevant date.” (para 145) In Farbwerke Hoechst v Unichem Laboratories (1968), the Bombay High Court held that “The specification and claims are addressed to those with a high degree of knowledge of the field of science to which they relate, particularly when they relate to chemistry and allied subjects” (p 65).

4The notional skilled addressee will vary with the facts and circumstances of each case, depending on the subject matter of the invention. The subject matter will be crucial in determining the addressee of the patent. The addressee will be expected to have ‘a practical interest in the subject matter’ of the invention having ‘practical knowledge and experience of the kind of work in which the invention is intended to be used’. (Catnic Components Ltd v Hill & Smith Ltd (1982) RPC 183, p 242.) His interest in the subject will enable him to read a document assiduously, regardless of how immensely boring it is. (Technip France SA’s Patent (2004) RPC 46, para 79 (CA).) In certain cases, the skilled person will be required to exercise a high degree of skill in meticulous and detailed operations that may be time-consuming. (See Genentech Inc’s (Human Growth Hormone) Patent (1989) RPC 613, p 619.)

5The subject matter will also determine whether the addressee is an individual person or a composite entity. (‘If the art is one having a highly developed technology, the notional skilled reader to whom the document is addressed may not be a single person but a team, whose combined skills would normally be employed in that art in interpreting and carrying into effect instructions such as those which are contained in the document to be construed.’ See General Tire & Rubber Co v The Firestone Tyre and Rubber Co Ltd (1972) RPC 457, p 482, [1971] FSR 417, p 443.) In cases involving advanced technology, it could be a team of members having different technical skills and knowledge, regardless of whether the members of the team worked as a single unit or individually. (‘I am satisfied that the notional skilled addressee of the specification of the patent in suit must be taken to be a team including microbiologists experienced in such recombinant DNA techniques as those involved in gene cloning and probably, though not necessarily, a chemist or chemists skilled in the synthesis of biochemical compounds.’ See Genentech Inc’s (Human Growth Hormone) Patent (1989) RPC 613, p 619, per Falconer J. See also Optical Coating Laboratory v Pilkington (1995) RPC 145, p 156.) The addressee may be assumed to know the basic principles of patentability. (‘In the modern world of science such as the sphere in which teams of highly qualified molecular biochemists, protein sequencers, protein chemists and others work, the artisan has receded into the role of laboratory assistant and the others have become segregated into groups of highly qualified specialists in their own spheres, all of whom must possess a high degree of inventiveness. If this were not so the specialists would not have been there at all.’ See Genentech Inc’s Patent (1989) RPC 147, p 214 (CA).) (Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] 1 All ER 667, (2005) RPC 9, para 78, per Lord Hoffmann.)

6In The Chinese University of Hong Kong v Assistant Controller of Patents & Designs (2023) the Madras High Court held, of whether a claimed process is diagnostic under s 3(i), that “Such determination should be made by assuming that a person(s) skilled in the art, including a medical doctor, examines the claims and complete specification.” (para 41) It held that “It bears repetition that such capability of the process should, in turn, be determined by assuming that a person(s) skilled in the art, including a medical doctor, examines the results.” (para 46) On the claims before it, it held that “person(s) skilled in the art would be able to arrive at a diagnosis as to whether a specific chromosomal aberration, such as an aneuploidy, exists by adopting this process.” (para 50) In Geron v Assistant Controller of Patents and Designs (2026) the Delhi High Court held that “The test is whether the claimed process is inherently capable of enabling a diagnosis for treatment, assuming a person skilled in the art ... including a medical doctor ... assesses the claim and its results.” (para 25)

7The court will allow expert evidence in determining what the skilled addressee knew. The court shall construe the specification and its claims in the light of the common general knowledge of such an addressee. (Hoechst Celanese Corpn v BP Chemicals Ltd [1999] FSR 319, pp 325-326 (CA).) The court will have to construct patents objectively as ‘a reasonable person to whom the utterance was addressed would have understood the author to be using the words to mean’. (Kirin-Amgen Inc v Hoechst Marion Roussel Ltd (2005) RPC 9, [2005] 1 All ER 667, para 32.) The notional skilled addressee should be the same entity for the purposes of determining obviousness and sufficiency of an invention. (Halliburton Energy Services Inc v Smith International (North Sea) Ltd [2006] EWCA Civ 1715, para 22 (CA).)

8The second step would be for the court to identify the person skilled in the art, ie, the notional skilled addressee to whom the patent is addressed. The court should put itself in the shoes of the person skilled in the art at the priority date of the claim and impute to him the ‘Common General Knowledge’ in the art as on that date. The court will have to determine whether at the relevant time, the skilled man perceived any problem which required to be solved. (See Dyson Appliances Ltd v Hoover Ltd (2001) RPC 26, para 153 (Pat Ct).)

9In Merck Sharp and Dohme v Glenmark Pharmaceuticals (2015) the Division Bench held that “the Court must not reinvent the wheel and mandate disclosures of techniques and product rehearsed in the industry already, but only examine what is new in the invention and how to arrive there from the state of the art.” (para 48)