The importance of semantics

The respondent, Kusile, had convinced the court of first instance that the patent, directed to ventilation systems for mining operations, was liable to revocation on the basis of lack of inventive step. On subsequent appeal, the court disagreed.

Kusile raised the following grounds in support of its claim for revocation (brought in reaction to a claim for infringement):

The claims of the patent were not based on matter disclosed in the patent specification;

The claims were otherwise unclear; and

The patent failed to sufficiently describe, ascertain and where necessary illustrate and exemplify the invention and the manner in which it is to be performed, thereby preventing the skilled addressee from performing the invention.

Many of the arguments on appeal (including that of inventive step) revolved around the words “rigid material” as used in the specification. In relation to the ground of insufficiency, without any specification-based dictionary for the term (and also without any special meaning derivable from the industry), the Supreme Court concluded that the phrase must be given its ordinary grammatical meaning.

Three expert witnesses offered testimony. This was done in order to construe the claims purposively, meaning these must not be read in isolation but instead be read in the context of the whole of the specification. A court’s understanding of the specification through an expert’s eyes would also answer the ground of lack of clarity.

Meanings that are consistent with that of the overall specification are meanings to be accepted as demonstrative of the intention of the author (and through it the patentee) at the time of drafting.  A dictionary having several meanings of a word provides a guide to its interpretation, bearing in mind its context in the specification.

The court also described who the skilled addressee is. In summary he or she is someone who is expected to bring reasonable intelligence to bear on the language of the specification, and who, while not required to struggle unduly with it, is to make the best of it and not adopt an attitude of studied obtuseness.