Case: Root Quality Pty Ltd v Root Control (2000) 49 IPR 225
Outcome: approved
For present purposes, however, it is helpful to refer specifically to several principles that have particular resonance with the circumstances of this case: (1) The underlying consideration in the construction of the patent is that it is a public instrument, conferring a public monopoly, that is meant to define the monopoly in such a way that it is not capable of being misunderstood: see eg Pfizer at 52 [247]. The patentee must define the invention with sufficient precision to permit the monopoly to be determined and to allow the general public to identify from the words of the claims the conduct that is prohibited: see eg Clorox at 261 [18]. (2) The claims define the invention which is the subject of the patent. They must be construed according to their terms by applying the ordinary rules of construction that apply to any written instrument: see eg D&eacute;cor at 400; Clorox at 260 [15]. (3) The claims must be construed in the context of the specification as a whole. The rest of the specification may explain the background to the claims, assist in ascertaining the meaning of technical terms, or aid in resolving ambiguities in the construction of the claims: Clorox at 260 [16]; Sachtler at 381 [42]. (4) Although the claims are to be construed in the context of the specification as a whole, 'the settled rule is that it is not permissible to vary or qualify the plain or unambiguous meaning of the claim by reference to the body of the specification': see Interlego per Barwick CJ and Mason J at 478. Further, 'it is not legitimate to narrow or expand the boundaries of monopoly as fixed by the words of a claim by adding to those words glosses drawn from other parts of the specification. Similarly, if a claim be clear it is not to be made obscure simply because obscurities can be found in particular sentences in other parts of the document': Welch Perrin at 610 per Dixon CJ, Kitto and Windeyer JJ; see also Clorox at 261 [17]. (5) A patent specification must be given a purposive rather than a purely literal construction. This involves construing the claims in a practical, commonsense manner, avoiding too technical or narrow a construction of the claims, and preferring a construction under which the invention will work to one where it may not work: Pfizer at 53-54, citing Nesbit Evans Group Australia Pty Ltd v Impro Ltd (1997) 39 IPR 56. It also means construing the claims in light of what a reasonable person to whom the patent was addressed would have understood the language of the claim to mean: Kirin-Amgen at 453-454 [30], [32] and [34] per Lord Hoffman. (6) The hypothetical addressee of the patent specification is the non-inventive person skilled in the art before the priority date. The words used in the specification and the claim are to be given the meaning that the skilled addressee would attach to them, both in the light of his or her own general knowledge and what is disclosed in the body of the specification: Clorox at 261-262 [20]; D&eacute;cor at 391; PhotoCure at 85 [170]. (7) The proper construction of the specification is a matter of law for the Court to determine. However, evidence can be given by experts on the meaning which those skilled in the art would give to technical or scientific terms and phrases and on unusual or special meanings given by such persons to words that might otherwise bear their ordinary meaning: see Clorox at 262 [21]; see also Root Quality Pty Ltd v Root Control (2000) 49 IPR 225 ( 'Root Quality' ) at 237 [49]. 65 As patent specifications and claims must be construed in light of the common general knowledge of a person skilled in the art before the priority date, it is necessary to ask: who is the skilled addressee? Various descriptions have been given to the skilled addressee, including the 'notional skilled addressee', the 'uninventive skilled worker in the particular field', the 'non-inventive worker in the field', the 'person skilled in the art', the 'non-inventive hypothetical skilled addressee', and 'those likely to have a particular interest in the subject matter of the invention': Root Quality at 241 [70]-[71] per Finkelstein J. The person skilled in the art is a 'relative expression which does not identify any specific person' and may consist of a team of persons with combined skills: Root Quality at 242 [71]; see also The General Tire &amp; Rubber Company v The Firestone Tyre and Rubber Company Limited [1972] RPC 457 ( 'General Tire' ) at 485. 71 In Root Quality at 241-242 [71], Finkelstein J observed that, generally speaking, the skilled addressee is the person who works in the art or science with which the invention is connected. He or she is a person, or team, likely to have a practical interest in the subject matter of the invention: at 241-242 [71].