Ancon Ltd v ACS Stainless Steel Fixings Ltd

Patent claims must be construed purposively in their technical context. Under Article 69 of the EPC, claim language determines the extent of protection, while the description and drawings help interpret it for the skilled reader. Purpose informs meaning but cannot erase a deliberate limitation or create a general doctrine of equivalents.

Where a new technical shape is described by an imprecise composite expression, the court must ask what the skilled person would understand it to convey. A technically minor difference may still fall within the claim if it lies within that contextual meaning. Functional parts of the claimed shape may matter more than a non-contact surface.

Ancon appealed from Patten J’s decision in the Patents Court, reported at [2008] EWHC 2489 (Pat). The patent was held valid, but ACS’s channel assembly was held not to infringe.

Claim 1 covered a channel assembly with a fixing head having a generally elliptical cone shape. ACS’s assembly possessed the claimed features except that the top of its bolt head had been filed down and did not retain an oval shape. The central issue was the proper construction of that phrase and whether the modified head infringed claim 1.

Lord Justice Jacob delivered the leading judgment and Lord Justice Waller agreed. The appeal was allowed.

1. Construction principles. The extent of protection was governed by Article 69 of the EPC. The claim terms determined the scope, while the description and drawings were used to interpret them in context. The relevant reader was the skilled person equipped with the common general knowledge. The court applied the purposive approach summarised in Halliburton v Smith [2006] RPC 25, informed by Kirin-Amgen v Hoechst Marrion Roussel [2005] RPC 169 and Catnic v Hill & Smith [1982] RPC 183.
2. Meaning of the claim. Generally elliptical cone shape was not a strict geometrical requirement. The skilled reader would understand that the purpose of the head’s shape was to produce the camming action against the channel. The relevant parts were the sides which co-operated with the channel, rather than the top, which did not contact it. The description and figures showed that vestiges of an ellipse were sufficient and that a complete oval did not run through every cross-section.
3. Rejected literalism. The court rejected arguments based on meticulous verbal analysis, the alleged need for an oval portion, and the proposition that the patentee could have chosen clearer wording. Purposive construction did not disregard the claim language, but it required the court to determine what that language conveyed in context. There was no general doctrine of equivalents; the result followed from the meaning of the claim itself.
4. Application. ACS’s bolt was essentially a filed-down version of the third illustrated embodiment and operated in the same camming manner. Its slight bevel produced no relevant technical difference. The bolt therefore infringed claim 1. The separate argument concerning the 2000 amendments to Article 69 and its Protocol was unnecessary to decide and was not determined.
5. Experts and order. Experts assisted the court on technology but did not construe the claims. The appeal was allowed on the issue of infringement. No further order was stated.

1. Court of Appeal (Civil Division): In [2009] EWCA Civ 498, the appeal was allowed. The court held that ACS’s assembly infringed claim 1.
2. High Court, Chancery Division (Patents Court): Patten J, in [2008] EWHC 2489 (Pat), held the patent valid but found no infringement.