The respondent (plaintiff) brought an action against the appellant (defendant) for infringement of South African Patent No. 95/0812, with a priority date of 3 February 1994. The patent related to seeding machinery designed for planting seeds in untilled soil. The defendant denied infringement and denied the validity of the patent, counterclaiming for its revocation on grounds that the invention claimed was not new, did not involve an inventive step, and was unclear. The Court of the Commissioner of Patents (Southwood J) dismissed the defences and counterclaim. The defendant appealed with leave of that court. The invention comprised a seeding assembly with a tube extending downwardly into a slot formed by a tine, a closing tool to partially close the slot, mounting means for height adjustment, and ground engaging means. The defendant relied on three US patents (Halford, Anderson, and Dreyer) predating the priority date to challenge novelty and inventiveness.
The appeal was upheld with costs. The orders of the court below were set aside and substituted with: (1) the plaintiff's action dismissed with costs; (2) the defendant's counterclaim for revocation of South African Patent No. 95/0812 granted, subject to the patent being provisionally revoked; (3) the revocation order to become fully operative if the patentee does not within one month file notice of an application to amend the patent, or having filed such application, withdraws it; and (4) the plaintiff ordered to pay the defendant's costs in respect of the counterclaim.
An invention does not involve an inventive step, and a patent is therefore invalid and subject to revocation, where the distinguishing feature between the claimed invention and the prior art would be obvious to a person skilled in the art. A feature is obvious if it is 'very plain' - that is, if a skilled person seeking to achieve a particular result (such as accuracy of seed placement) would naturally adopt that solution. The mere absence of a specific integer from a prior art document does not render that integer inventive if its adoption would be an obvious step to a person skilled in the art. Courts may draw on multiple documents forming part of the state of the art to determine what would be obvious. The assessment must be made without the benefit of hindsight.
The Court made several non-binding observations: (1) it noted that while expert evidence might be necessary in some cases to educate the court in the technology involved, it is not always necessary; (2) it observed that reliance on the projection of the tube into the slot as an inventive step appeared to be 'merely an opportunistic exploitation of the absence of that integer from the description in Dreyer' given that this feature was not mentioned in the specification's description of the background to and object of the invention; (3) the Court commented that if the inventor considered the projection inventive because it avoided seed displacement by wind, 'it is remarkable that no reference was made to it when describing the background to and the object of the invention'; and (4) the Court noted that the appellant's counsel advanced no adequate reason why a provisional revocation order should not be made to allow the patentee to amend the specification.
This case is significant in South African patent law for its application of the test for inventive step under section 25(1) of the Patents Act 57 of 1978. It reaffirms the four-part test from Ensign-Bickford for assessing inventive step and emphasizes the danger of hindsight in such assessments. The judgment clarifies that an invention must involve a step that is not obvious to a person skilled in the art, and that 'obvious' means 'very plain'. It demonstrates that minor variations on prior art that would be obvious solutions to skilled persons do not constitute inventive steps. The case also illustrates the court's willingness to consider multiple documents from the state of the art when assessing both novelty and inventiveness. Additionally, it confirms the availability of provisional revocation orders allowing patentees opportunity to amend their specifications under section 68 of the Act.
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