Lack of inventiveness is a ground for revocation under the present Act by reason of the provisions of section
25(1), (6) and (10) read with section 61(c). The relevant provisions of section 25 are as follows:
"25.
Patentable inventions.
(1)
A patent may, subject to the provisions of this section, be granted for any new invention which involves an
inventive step and which is capable of being used or applied in trade or industry or agriculture.
(6)
The state of the art shall comprise all matter (whether a product, a process, information about either, or
anything else) which has been made available to the public (whether in the Republic or elsewhere) by written
or oral description, by use or in any other way.
...
...
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(10)
Subject to the provisions of section 39(6), an invention shall be deemed to involve an inventive step if it is not
obvious to a person skilled in the art, having regard to any matter which forms, immediately before the priority
date of any claim to the invention, part of the state of the art by virtue only of subsection (6) (and disregarding
subsections (7) and (8))."
These provisions constitute a statutory code. In effect all available knowledge is the starting point and lack of
inventiveness only arises as an issue if the invention has, as it were, survived the attack on novelty. Expressions
used and tests formulated in earlier judgments must be used with care.
As is pointed out in Roman Roller CC and another v Speedmark Holdings (Pty) Ltd 1996 (1) SA 405 (A) at 413, in
order to apply these provisions to a particular case it is necessary to determine what the art or science to which the
patent relates is, who the person skilled in the art is and what the state of the art at the relevant date was. But
the inquiry, in my view, must then proceed further. After those factors have been determined, a more structured
inquiry must be undertaken. For this it is appropriate to adopt tests formulated in certain English authorities. The
tests proposed do not differ from some of the inquiries suggested in the earlier practice in our courts but they are
conveniently arranged in a suitable sequence in the case of Mölnlycke AB and another v Procter & Gamble Limited and
others (no 5) [1994] RPC 49 (CA) at 115. Four steps are identified. They include or restate in part what has been
said above but may be taken to conveniently list the inquiries to be made:
(1)
What is the inventive step said to be involved in the patent in suit?
(2)
What was, at the priority date, the state of the art (as statutorily defined) relevant to that step?
(3)
In what respect does the step go beyond, or differ from, that state of the art?
(4)
Having regard to such development or difference, would the taking of the step be obvious to the skilled man?
In the judgment of the court below the learned judge held that what was
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available to the public was "the mono tube which in the course of time was provided with a wax overbraiding". He
also held that the technique of overextrusion, particularly for detonator cords, was well known in the mid
1970's. He concluded that there were obvious ways to overcome the difficulties with the known tubes such as
asking Du Pont to provide a tube with greater adhesive properties or to reduce the core load or particle size of the
powder. The evidence bears all this out. The learned judge then held that "All the points taken individually may well
be correct. But it does not follow that the invention in its totality is obvious. That approach smacks of the armchair
critic and fails to take into account that each problem had first to be overcome and then everything has to be
integrated to produce an article which is acceptable in the market place". This proposition calls for further
consideration. It, in my view, does not sufficiently or adequately formulate the question to be posed. Firstly the
question to be determined is whether what is claimed as inventive would have been obvious not whether it would
have been commercially worthwhile. See Windsurfing International Inc v Tabur Marine (Great Britain) Ltd [1985] PPC
59 at 72. Secondly the emphasis must lie on the technical features. A passage in the judgment of Sir Donald
Nicholls, Vice Chancellor, in the case of Mölnlycke v Procter Gamble, supra, bears repetition. At 113 the Vice
Chancellor said:
"In applying the statutory criterion and making these findings the court will almost invariably require the assistance of expert
evidence. The primary evidence
Page 462 of [1998] 4 All SA 453 (A)
will be that of properly qualified expert witnesses who will say whether or not in their opinions the relevant step would have
been obvious to a skilled man having regard to the state of the art. All other evidence is secondary to that primary
evidence. In the past, evidential criteria may have been useful to help to elucidate the approach of the common law to the
question of inventiveness. Now that there is a statutory definition, evidential criteria do not form part of the formulation of
the question to be decided.
...
What with hindsight, seems plain and obvious, often was not so seen at the time. It is for this reason that contemporary
events can be of evidential assistance when testing the experts' primary evidence. For instance, many people may have
been industriously searching for a solution to the problem for some years without hitting upon the allegedly obvious
invention. . Yet again, evidence of the commercial success of the invention can lead into an investigation of the reasons for