Patent "Obviousness" and Related Matters - Breaking New Ground

In this article, the writer comments on a recent judgment in the Supreme Court of Appeal of South Africa handed down on 21 September 1998 [as yet unreported] in the matter between Ensign-Bickford (South Africa) (Proprietary) Limited & Others vs AECI Explosives & Chemicals Limited,. The issues addressed by the Court in the judgment relate to the validity of South African patent no. 79/3210 entitled "Low-energy fuse consisting of a plastic tube the inner surface of which is coated with explosive in powder form". Plewman JA (with the full court concurring) overturned and revised many established principles relating to the law of "obviousness" and particularly to the way that this is tested in South African law.

An invention, as this word implies, has to be "inventive". "Obviousness", as the opposite of "inventiveness", therefore forms part of patent law and relates to a ground of invalidity on which a patent can be revoked. The Ensign-Bickford judgment breaks new ground in that, to the writer’s knowledge, it is the first time that a Court has found a patented invention to be "obvious" under the current Patents Act 57 of 1978. It has been notoriously difficult to revoke a patent on this ground in the past, and the way that the Supreme Court of Appeal did so in this case sets new precedents and makes interesting reading.

First, the long established 3-step enquiry which has been referred to in many cases in South African patent law since its definitive formulation in the landmark Appellate Division case in Gentiruco A.G. vs Firestone (South Africa) (Pty) Ltd 1971 BP 58 (at 155G to 156A), through to the more recent Appellate Division case in, Roman Roller CC & Another vs Speedmark Holdings (Pty) Ltd 1995 BP 199 (at 213A, 215A and 219D), was cast aside by Plewman JA.

In brief, (and quoting from Speedmark Holdings (Pty) Ltd vs Roman Roller CC & Another 1993 BP 397 (at 405B to 406B), upheld an appeal in Roman Roller supra) the 3-step test as it stood before Ensign-Bickford entailed the following:

  1. A determination of what matter formed part of the state of the art i.e. had been made available to the public before the priority date of the patent, whether in South Africa or elsewhere, by written or oral description, by use or in any other way (the first step when read with Section 25(6) of the current Patents Act No. 57 of 1978).
  2.  Whether the invention claimed was, or comprises, a step forward on such matter which has been made available to the public (i.e. the "prior art" viewed collectively, which can therefore be "mosaiced together") [Speedmark case supra at 411A].
  3. Whether in the light of such matter available to the public, the step was inventive i.e. not obvious to a person skilled in the art to which the patent relates (the third step when read with Section 25(10) of the current Patents Act No. 57 of 1978).

Patent attorneys in South Africa have used this test for many years and it has proved to be a useful yard stick which can be applied consistently to a variety of different circumstances which can arise. Summarised, the abovementioned test for "obviousness" can be formulated as follows (Speedmark case supra at 408G to 409B):

"… it is to identify the differences that exist between these prior art documents and the alleged invention. And, if there are differences, the question is then whether there has been a step forward. If there is, then the final question is whether it required some inventiveness or would it have been obvious to a man skilled in the art."

The "inventive step" analysed in the third prong of the enquiry need not relate only to the claimed product, equipment or process, but to development stages before the invention is eventually arrived at. For example, the Appellate Division recognised in Miller vs Boxes and Shooks (Pty) Ltd 1945 AD 561 (at the bottom of page 584 of the judgment citing Halsbury, Laws of England, 2nd edition, volume 24, section 1122):

"An invention usually involves three stages. First, the definition of the problem to be solved or the difficulty to be overcome; secondly the choice of the general principle to be applied in solving the problem or overcoming the difficulty; and thirdly, the choice of the particular means to be used. Merit in any one of these stages, or in the whole combined, may support the invention"

In the recent Ensign-Bickford case, Plewman JA held (at page 23 of the unreported judgement) that the standard 3-step enquiry must proceed further, that a more structured enquiry must be undertaken, and that it would be "…appropriate to adopt tests formulated in certain English authorities." It is not clear why the judge of appeal felt the need to depart from the usual standard as he himself conceded that "…the tests proposed do not differ from some of the inquiries suggested in the earlier practice in our Courts…". Nevertheless, citing the case of Mölnlycke AB and Another vs Procter & Gamble Limited and Others (No.5) [1994] RPC 49 (CA) Plewman JA introduced into our law the following 4-step inquiry:

  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?

The Court did not reveal why it considered this formulation to be an extension of the standard enquiry, when some of the steps are repeated. On the other hand, if one considers the new test to be an entire reformulation of the old enquiry, then the rearranging of the steps and the splitting up of the test into four stages would seem to have important consequences as follows.

Rather than reviewing the relevant prior art as a first step, in order to establish whether the invention claimed has a "step forward" which could be said to be "inventive" (or "non-obvious"), a patentee is now required to pin his colours to the mast up front and lead evidence relevant to the (new) first question, and identify the inventive step said to be involved in the patent in suit. The prior art is then reviewed subsequently to see whether that alleged "step" can be identified in the prior art, or is different. In this way, Plewman J A appears to have turned the inquiry around.

The consequences of applying this new test were certainly felt by the patentee because it was in relation to the first (new) inquiry that the judge of appeal felt that the patentee’s evidence was lacking. The judge called this evidence "primary" evidence and at page 27 of the unreported judgment he states that "… very limited attention seems to have been paid to it in the evidence. The result is that the primary evidence is not particularly helpful."

But is this apparent lack of evidence filed on behalf of the patentee to show "inventiveness" a valid criticism when it has traditionally been incumbent on the defendant to lead evidence in support of "obviousness"? It has long been an established principle of our South African patent law that a patent is presumed valid until shown otherwise. The onus is on the defendant who argues invalidity of the patent to show that invalidity on any of the grounds it chooses to attempt to revoke the patent. By focussing on what the patentee has to say, and by asking the patentee to lead evidence relevant to (new) question one, it could perhaps be argued that some shifting of the onus has occurred. At the very least, the burden of evidence on the patentee to rebut a prima facie case of obviousness appears to have increased.

Let us contrast the Appeal Court’s new requirements in this latter regard with the position prevailing before the Ensign-Bickford case. For example, in the Firestone case supra (at 108B), the Appellate Division held (quoting with approval from Miller vs Boxes & Shooks supra [at pages 575/6]) that:

"It can be conveniently added here that the onus of proving that the patent in suit was invalid on any of the alleged grounds rested on Firestone, and that that onus could be discharged on a balance of probabilities."

This principle has been confirmed and followed in several cases since, for example, in Kimberly-Clark Corporation & Another vs Johnson & Johnson (Pty) Ltd 1983 BP 160 (at 162A) in which, as a point of academic interest only, Plewman JA appeared as counsel for the patentee. The Court in that matter held that "…the onus of proof that the plaintiff’s patent is described in the Buell patent (an alleged prior disclosure of the invention in issue) rests on the defendant…" and concluded that the defendant [emphasis added], by not leading an expert to address the Court on the alleged invalidating Buell disclosures, had "…set itself an onus which is difficult to discharge…". The validity of the patent was accordingly upheld. In the Ensign-Bickford matter, on the other hand, a lack of evidence filed on behalf of the patentee to support the contrary position, namely "inventiveness", contributed to the patent’s downfall.

Perhaps the Court’s most remarkable departure from traditional principles in the Ensign-Bickford case relates to the nature of the evidence to be filed on the issue of "obviousness" and again concerns the issue of what Plewman JA called the "primary evidence".

Previously, the opinion of any witness as to the validity or otherwise of a claimed invention was totally irrelevant. Of course, expert evidence could be led, for example, to assist the Court in explaining the meaning of technical terms (see for example the Kimberly-Clark case supra at 172G), or to identify certain alleged invalidating features disclosed in the prior art, or to address the Court on the date of such disclosures, but it has been stressed by our Courts, most notably in the Firestone case supra (at 139D) that:

"Again it is emphasised, the opinions of the expert witnesses that a document does or does not anticipate a claim of the patent in suit must be disregarded for that is for the Court to decide…"

and later in the same judgment (at 167B – C) that:

"The only real and substantial issue here therefore is whether that step forward was obvious. Meyer testified that it was not; Drs Bull and Garvey expressed the opposite view. Those opinions have to be disregarded (see British Celanese Limited vs Courtaulds Ltd, 52 RPC at page 196, quoted earlier in this judgment). The Court, eschewing all hindsight induced by the patent in suit, must itself [emphasis added] decide, in the light of what was then common knowledge, whether or not the combination process (and not merely its individual integers) was proved by Firestone to have been obvious."

As against this, Plewman JA in the Ensign-Bickford case held at page 26 of the unreported judgment (again referring to the Mölnlyck vs Procter & Gamble case supra):

"In applying the statutory criterion and making these findings the Court will almost invariably require the assistance of expert evidence. The primary evidence will be that of properly qualified expert witnesses who will say whether or not in their opinons [emphasis added] 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."

Secondary evidence, such as "commercial use" (i.e. evidence relating to the success of the invention subsequent to the filing of the patent), or "a long felt want" is to be considered as no more than an aid in assessing the primary evidence. Accordingly, it would seem that any party to a patent case to be decided in the light of the Ensign-Bickford case must ensure that evidence is led in relation to an opinion of at least one appropriate expert witness attesting to the inventiveness, or otherwise as the case may be, of the invention in issue. This is an aspect which clearly would have been considered irrelevant in the light of the authorities prevailing before the handing down of the recent Ensign-Bickford judgment.

In applying the newly formulated test, Plewman JA found himself in disagreement with the finding of the Court below and held that the claim for revocation on the ground of "obviousness" must succeed and the appeal was upheld.

The judge of appeal conceded (at page 35 of the unreported judgment) that in matters of this nature, it is customary for the Court to afford the patentee an opportunity to apply for an amendment which may save the patent. Leave to amend a patent, in order to bring it into a "narrower" form in which it distinguishes over the prior art of record and hence be "saved", can be granted in terms of Section 61(3) of the current Patents Act. Although counsel for the plaintiff made no application for such a request, the judge felt that there were factors present which would render any suspension of his revocation order inappropriate, but came to his decision in an interesting way.

The Court held that the patent specification failed to provide instruction as to how a balance between certain integers of the claimed invention was to be achieved and mero motu concluded that the description contained in the patent specification was "insufficient". "Insufficiency" is another ground of revocation on which a patent can be attacked and Plewman JA held that the patent was fatally invalid on this ground and stated (at page 36 of the unreported judgment) that "…it is difficult to see how the patent could be improved."

The ground of "insufficiency" had not been relied on at the trial, nor at the hearing of the appeal and this is acknowledged by Plewman JA in his judgment. The mero motu finding of "insufficiency" therefore makes new law and can be contrasted with the situation prevailing before the Ensign-Bickford case. For example, as has been mentioned above, in the Kimberly-Clark case supra the invention in issue (a diaper having "gross transverse rugosities") was held to have been prior disclosed in an earlier patent referred to as the "Buell" patent. The only ground of invalidity relied upon was that the claimed invention was not new. The Court in that case (O’ Donovan J) held (at 161 G to 162B):

"…it must be accepted that the patent in suit is not open to attack on any other ground, that for example its subject matter is useful and inventive, and that the specification sufficiently discloses [emphasis added] or explains the invention."

Unfortunately, when testing the effect of his finding in this regard, Plewman JA stated: "More important, however, is the fact that the patent has now expired so that no amendment could in any event be applied for or be effective…". At the time of writing this article, the patent is presently in force and therefore capable of being amended.

The Court also criticised counsel on both sides in relation to the heads of argument filed in the matter, more particularly in observing that very little had been submitted in relation to the law of obviousness and the evidence led in relation thereto. This observation should serve as a warning to practitioners, but hopefully also as an encouragement that the ground of "obviousness" can no longer be considered to be an impenetrable battlefield on which to launch an attack on a patent. Equally, a patentee seeking to shore up his defences should ensure that appropriate evidence, including the opinion of at least one expert witness, is led in support of the inventive steps claimed in the patent in issue.

Hugh Moubray is a patent attorney of the High Court of South Africa and the partner in charge of patent litigation at Spoor & Fisher.

Date published:
Author: Hugh Moubray

Tags: patents ensign-bickford aeci explosives & chemicals