Case Comment

Ernest Scragg & Sons v.
Leesona Corp.,

citation(s): [1964] Ex. C.R. 649, 45 C.P.R. 1 (Ex. Ct. per Thorson, P.)

copyright 1997 Donald M. Cameron




The Decision

A p. 54

"While the Golden Rule of construction of a document, namely, that its words should be given their plain and ordinary meaning applies to the claims of a patent it is a fundamental principle of patent law that a patent specification should be construed fairly. The Court must recognize the fact that just as there may be imperfections in speech and words may be used that do not convey the meaning of the speaker as precisely as the use of more appropriate words would do so there may be lack of precision in the use of the words in a patent specification and in a patent claim, but this must not be allowed to defeat the claim if its meaning, notwithstanding the misuse of some of its words, would be plain to the person of ordinary skill in the art to which the invention covered by the patent relates. The Court must, therefore, construe the claims in issue accordingly without regard to any faults of expression or misuse of words that do not mislead the addressee of the patents in issue."

At p. 57

"While the golden rule of construction requires that the words of a patent claim should be given their plain and ordinary meaning this is on the assumption that the words have a plain and ordinary meaning, but it is well established that the words may bear a "special or unusual meaning by reason either of a dictionary found elsewhere in the Specification or of technical knowledge possessed by person skilled in the art": vide Lord Russell of Killowen in the E.M.I. v. Lissen case, supra, at p. 41. There he went on to say:

"The prima facie meaning of words used in a claim may not be their true meaning when read in the light of such a dictionary or of such technical knowledge; and in those circumstances a claim, when so construed, may bear a meaning different from that which, it would have borne had not such assisting light been available. That is construing a document in accordance with the recognized canons of construction."

"It is established that experts in the relevant art may give evidence of the meaning of technical terms and expressions in a patent claim as they would be understood by the assumed addressee of the patent. The permissive rule, together with the limitation of its applicability, was defined by Lord Buckmaster in Charlesworth Peebles & Co. v. British Thomson-Houston Co. Ltd. (1925), 42 R.P.C. 180 at p. 208, in the following terms:

"As, however, in ordinary cases, the existing circumstances in which documents were prepared, the relationship of the parties and the interpretation of terms of art are the proper subject-matter of evidence, so in specification of patents the state of knowledge in the craft, art or science to which the specification is directed and the explanation of technical terms, words and phrases are the proper subject-matter of testimony to aid interpretation, but, beyond this, evidence affecting construction should not be allowed to stray".


At p.76:

"The provision of prima facie validity extends to all the attributes of patentability that an invention must have in order to be patentable under the Act. The attributes of novelty, utility and inventive ingenuity or lack of obviousness are all presumed to be present in an invention for which a patent has been granted until the contrary is shown. The provision also extends to the obligations imposed by law on a patentee and the requirement specified in the Act. Compliance with them is presumed until the contrary is shown. It follows that the onus of showing that a patent is invalid lies on the party attacking it, no matter what the ground of attack may be."


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