This was a case of nuts and bolts. More particularly, it is a case of channel assemblies” which are used in the construction industry and are made up of a metal channel which is cast into concrete and a bolt that can be moved along the channel to its required position and then turned 90° so as to lock in place.
The channel is anchored in the concrete, and the fixing can support an extremely heavy load - up to ¾ tonne or the weight of a small car. Prior art bolts were rectangular, with opposite corners rounded to facilitate sliding and turning (see Fig.2).
In the case of the assembly claimed in the patent, the channel was V-shaped and the bolt head, which is turned in the channel, was defined as having a generally elliptical cone shape.
This caused a camming effect between the head and the channel to improve load transference. Ancon v ACS Stainless Steel Fixings The patent described symmetric and asymmetric bolt heads.
The asymmetric embodiment was shown in Figs.5 and 6. The efendant’s product (Fig.7) included all the features of the claimed evice, except that the bolt head was modified so that the top did not have an elliptical shape.
Notice the similarity to Fig.6. The parties did not dispute that it is just like the example of Fig.6 of the patent but with the top of the head filed down so that there is no ellipse on the top. Notice also the similarity with the prior art in Fig.2, which has diagonally opposite corners rounded off but does not have opposite sloping sides.
Truly this was a finely balanced case. The Patents Court found there to be no infringement because the phrase “generally elliptical cone shape” described shapes, all of which retain the essential feature of an ellipse. Alternative constructions gave no real recognition to the patentee’s reference in the claims to the bolt head being elliptical, and the judge said it is important to bear in mind that the patentee may have a number of reasons for limiting the scope of the claims which are not always evident to a subsequent reader. The patent may, for one reason or another, claim less than it teaches or enables.
The Court of Appeal allowed Ancon’s appeal and found there to be infringement.
Based on a purposive construction of the claim, the Court of Appeal found that the skilled person would have regard to the purpose of the shape of the head of the bolt and recognise that the shape was to achieve the camming action. The sides of the bolt, and not the top, were the parts that cooperated with the channel. Since the bolt of the respondent’s product had the “vestiges of a true ellipse, sufficient for the necessary camming action”, the claim was considered to be infringed.
It did not help the defendent (respondent) that the Opposition Division for the European Patent had already considered the question in relation to an opposition to this patent, saying: “It is clear for a skilled person that, in contrast to a strict elliptical cone shape, with the expression generally elliptical the cross section of the cone should include any rounded non-circular form. The restriction to an elliptical cone shape would be an undue restriction of the scope of protection, having regard to the disclosure of the patent in suit.”
Cases of purposive construction such as this balance the two opposing principals of the Protocol on the Interpretation of Article 69, viz. fair protection for the patentee against reasonable certainty for third parties, and it can be difficult to anticipate which way a particular court will lean. In the past it has been perceived that UK courts tend to lean towards certainty for third parties, but not in this case.
The respondents (ACS) put forward ten good arguments in favour of a narrower construction, but Jacob LJ. dismissed each argument, saying “there is nothing in any of them which has regard to the purpose of the features of the claim. . . . The purpose of the shape is to achieve the camming action into the corners of the channel. The shape of the top of the bolt, which does not come into contact with the channel is immaterial to this” (emphasis added). Notice how, in Figs 8 and 9, when the bolt is turned in the V-shaped channel, the top of the cone (lowermost in the figures) does not touch the channel.
1. An ellipse or oval is not present throughout most crosssections of the bolt of the patent. Only very near the top and at the top is there such a cross-section. So a complete elliptical or oval shape is essentially not present in what is shown. Indeed, so far as it is present, it performs no useful function.
2. Arguments based on the geometry of a cone and of an ellipse are a lawyer’s argument and non-purposive.
3. The ACS bolt cams in just the same way as Fig.9 – it is essentially a filed down version of it.
4. It is not relevant that the cross- section may be the same as the prior art (not “elliptical”). Yes, the skilled man would recognise in Fig.9 that the cross-section at the bottom is the same as in the prior art, but it does not matter that the expression “elliptical” would not have been used to describe the prior art.
5. It is quite true that you cannot ignore or depart from the claim language. But one is not doing that when trying to ascertain what the skilled reader would understand the patentee to have meant by the claim language he used.
6. One can nearly always argue that the patentee could have chosen better language (“If the draftsman had meant that, he could easily have said so”) but this argument “seldom assists and does not do so here”. The patentee was trying “to describe something which, at any rate in his opinion, is new; which has not existed before and of which there may be no generally accepted definition.” You need to start from some point of reference to a known sort of shape (here an ellipse and a cone). That is what the patentee was obviously doing.
7. It might have been possible to attempt a claim in functional terms – “so shaped that it will cam …” but such claims also have their difficulties, and some patent offices can be resistant to them on the grounds of undue width.
8. The Judge’s error was in saying that the shapes shown in the patent all “retain the essential feature of an ellipse.” They do not in any relevantly technical sense. Except for the very top, the cross-sections are not oval – they have the mere vestiges of oval shapes.
9. Expert evidence that the ACS bolt was not “generally elliptical” was not decisive. This was a question for the Court. The function of experts is to aid the court’s understanding of the technology, not to construe the claims.
10. Finally there was some evidence that the ACS bolt did not function in quite the same way as one with a true elliptical cone, but this was disregarded because the “fit” was so similar that there was no technical difference. (Additionally, the evidence addressed infringement of a dependent claim. It might have been relevant if infringement of that claim was at issue.)