[19] With regard to context, the advantage of the invention is the enhanced safety as a result of the support
provided by the telescopic props. Further, the detailed description of the invention in the specification,
specifically disavowed a restriction to linear positioning of the carriage between the props and a limitation to
two props. It provides that "the drill need not be located linearly between the pair of props, but may be
generally between them. This would more likely be the case where an additional prop or additional props are
used". Once there are more than two props which are not configured in a straight line, the carriage may be
located between the props, without being linearly between them.
[20] Both parties led expert evidence with regard to the understanding of persons skilled in the art. Elbroc's expert
understood the word "between" to mean that the carriage could be offset from the linear line between the
props and could also be off centre. Both experts understood the "linearly between" position of the carriage to
be the optimal solution to the problem that the patent solved. Needless to say the optimal solution is not the
only solution.
[21] Turning to purposive interpretation, Orica's argument in this regard was raised as an alternative to the above
stated submissions. Within the context of patent construction, unlike literalism, this approach takes into
Page 805 of [2017] 2 All SA 796 (SCA)
account the practical knowledge and experience of the person skilled in the kind of work in which the
invention is intended to be used.18 It considers that a person skilled in the art would understand whether
strict compliance with a particular word or phrase was intended and whether a variant of a word would have
an effect upon the way the invention works, such that the impugned object would fall outside the monopoly
protected in the claims and there would be no infringement.1 9
[22] The facts in this appeal bear a striking resemblance to Catnic Components Limited and another v Hill & Smith
Limited2 0 which was the leading English authority on purposive construction prior to the enactment of the UK
Patents Act in 1977. Firstly, similarly to the defendant in Catnic, Elbroc admitted to having taken all but one of
the essential features of plaintiff's patent. Secondly, there is no evidence that the variant integer that
features in Elbroc's drill rig has any material effect on the functioning of the Orica drill rig.
[23] In Catnic the plaintiffs were the registered proprietors of a patent for novel, commercially successful steel
lintels invented by the second plaintiff. The defendants, intending to enter the market for galvanised steel
lintels, obtained a copy of the plaintiffs' experimental lintel drawings from which they (the defendants) made
their lintels. On being cited for infringement of the patent the defendants produced a lintel which differed from
their first one and from the plaintiffs' only in that its rear support member, instead of being perpendicular to
the base, was inclined 6 or 8 degrees from the vertical position. Claim 1 of the patent required the rear
member to "extend vertically". The angle of 6 to 8 degrees in the defendants' lintel reduced the load bearing
capacity of the rear member by 0,6 and 1,2% respectively. This reduction had a negligible effect on the
functioning of the member. The Court held that it would not have been the understanding of persons with the
relevant practical knowledge and experience that strict compliance with the words "extending vertically" was
intended by the patentee. Moreover, "extending vertically" was, in context, capable of meaning, " near enough
to vertical to enable the back plate to perform satisfactorily all the functions that it could perform if it were precisely
vertical".2 1 (My emphasis.)
[24] There is nothing in claim 1 of the patent to show that Orica intended that a drill carriage located only linearly
between the props was essential to its invention, or that a person skilled in the art would understand that
the word "between" was intended to be used as a "word of precise meaning".2 2 Moreover Elbroc's expert,
Mr Johannes Fourie admitted that although the Elbroc drill carriage is located off the notional line between the
props it was the Elbroc drill rig was still located sufficiently close to the line to be able to gain support from the
props.
Page 806 of [2017] 2 All SA 796 (SCA)
[25] Counsel for Elbroc relied upon the decision in KirinAmgen Inc and others v Hoechst Marion Roussel Ltd.2 3 In
support of Elbroc's contentions regarding the interpretation of claims in a patent. For the reasons set out
below I do not agree with the submission.
[26] In KirinAmgen, the issue was whether the claims of a European patent granted to KirinAmgen Inc in relation
to a protein which stimulates production of red blood cells in the bone marrow, were infringed by
Transkaryotic Therapies Inc and Hoechst Marion Roussel Ltd, in circumstances where there was striking
similarity between the technologies used by the two parties for producing the hormone erythropoietin. The
Court found no infringement on the facts of the case. Indeed, the Court held that patent claims are the
decisive basis for determining the extent of protection.24 But it also approved the basic principles of patent
interpretation enunciated in Catnic. The court considered articles 69 and 84 of the European Patent
Convention ("EPC"). Article 84 provides that:
"The claims shall define the matter for which protection is sought. They shall be clear and concise and supported by
the description."
Article 69 states:
"The extent of the protection conferred by a European patent or European patent application shall be determined by
the terms of the claims. Nevertheless the description and the drawings shall be used to interpret the claims."
[27] Lord Hoffman then sketched the background of these provisions, explaining that article 69 was the result of a
compromise between what was viewed as the unduly narrow and literal construction approach of the United
Kingdom, and the other contracting European States whose approach had been to look at the essence of the