Maccaferri Ltd v Hesco Bastion Ltd

Patent claims must be construed purposively, by reading the claims in the context of the specification and drawings through the eyes of the skilled reader. Ordinary descriptive words should not be given an artificially narrow meaning where the patent’s purpose is achieved in substance.

For infringement, a structure may fall within a claim despite a minor difference in its operating sequence where the difference has no material effect, that would have been obvious as immaterial at the relevant date, and strict compliance was not intended to be essential. Obviousness is assessed by identifying the inventive concept, the skilled person’s common general knowledge, the differences from the prior art and whether those differences required invention.

Hesco Bastion’s patent concerned a prefabricated wire-mesh cage which could be transported in a flattened form and erected on site by unfolding, without further fixing. Maccaferri imported and sold the Flex-Mac, a rectangular multi-cavity cage which operated in substantially that way but required a final skewing movement to open the cavities.

The Patents County Court held that claim 1 was valid and infringed. On appeal, Maccaferri challenged the construction of the claim, infringement and the finding that the claim was not obvious over Czinki. The central issues were the meaning of “folded concertina fashion”, the significance of the additional opening movement, and the correct assessment of inventive step.

Auld LJ delivered the leading judgment. Robert Walker LJ and Sir Christopher Slade agreed. The appeal was dismissed.

1. Construction. Section 125 of the Patents Act 1977, read with the Protocol on the Interpretation of Article 69 of the European Patent Convention, required the claim to be construed by balancing fair protection for the patentee with reasonable certainty for third parties. The court had to read the claim in the light of the specification and drawings, giving words their ordinary meaning as understood by the skilled reader.
2. The word “concertina” had no technical meaning in the relevant trade. In context, “folded concertina fashion” meant folding in a broadly zigzag manner. It did not require reproduction of the bellows-like form of a musical concertina, hexagonal cavities, parallel end walls or automatic opening without any further movement. The essence of the invention was a factory-made hinged structure capable of rapid erection by unfolding without further fixing of the Penfold type.
3. Infringement. Flex-Mac satisfied the claim despite having one side panel per cavity and requiring a small final skewing movement. Alternatively, that movement was an immaterial variant under the Improver approach. It had no material effect on how the invention worked, that would have been apparent to the skilled reader, and the language of the claim did not make strict compliance essential.
4. Validity. Under section 3 of the Patents Act 1977, the claim involved an inventive step if it was not obvious to the skilled person. The court adopted the four-stage Windsurfing inquiry: identify the inventive concept; identify common general knowledge; identify differences from the prior art; and ask whether those differences were obvious without hindsight.
5. The trial judge was entitled to identify the inventive concept by reference to the essential elements of claim 1, rather than merely as an “expandable cage structure”. The finding that hinged multi-cavity gabions were not obvious over Czinki was a mixed question of fact and law, and there was no error of principle or unsustainable conclusion warranting appellate interference.

The patent was valid and claim 1 had been infringed. Appeal dismissed.

• Court of Appeal (Civil Division): Maccaferri Ltd v Hesco Bastion Ltd [2002] EWCA Civ 264. Appeal dismissed; the Patents County Court’s findings that the patent was valid and infringed were upheld.
• Patents County Court: The court held that claim 1 was valid and that Maccaferri had infringed it. The date of that decision was 27 April 2000.