AP Racing Ltd v Alcon Components Ltd

Patent claims are construed through the eyes of the person skilled in the art, using the language of the patent as a whole. A claim is not rendered uninfringeable merely because its boundary is difficult to apply, provided the skilled person has sufficient practical and visual guidance.

A peripheral stiffening band must be materially distinct from limb material at the ends of the cylinder housings. It must make a material contribution to stiffness and be clearly more than minimally asymmetric when viewed in plan about any lateral axis. The court must identify the band’s boundaries by applying the patent’s visual and structural clues to the individual product.

The claimant alleged that eight further models of the defendant’s racing-car brake calipers infringed UK Patent No 2,451,690. The action followed earlier infringement proceedings concerning other caliper models and was limited at trial to infringement.

The central issues concerned the construction and application of claim 1, particularly the requirements for shaped cylinder housing portions, peripheral stiffening bands, interconnection of the housing portions, and asymmetry about a lateral axis.

1. Construction. The claim was construed from the perspective of the skilled braking engineer, applying the established approach in Kirin Amgen Inc v Hoechst Marion Roussel Ltd [2004] UKHL 46. “Profiling” meant shaping. Claim 1 required a shaped housing portion around each cylinder, but imposed no particular shape.
2. Peripheral stiffening band. The expression was not a term of art. In the context of the patent, it meant a single band of material lying at the periphery, appreciably beyond and distinct from the limb material at the ends of the cylinder housings. It had to stiffen the caliper to a material degree.
3. Asymmetry. Absolute mathematical asymmetry was not required. Minor asymmetry was irrelevant. A band fell within the claim if it was clearly asymmetric to the eye about any lateral axis; conversely, it was outside the claim if there was a lateral axis about which it was symmetrical. No separate requirement existed that the asymmetry affect torque response or braking efficiency.
4. Identifying the band. The band and limb were mutually exclusive parts, although their boundary could be difficult to determine. Openings and webs could indicate that surrounding material formed part of the band. Material resembling ordinary limb material, without such indications, was likely to remain limb material. The claim was difficult but just sufficiently workable for the skilled person, applying the principle discussed in Millikin Denmark AS v Walk Off Mats Limited [1996] F.S.R. 292.
5. Application. CAR 9549Y73 infringed. Calipers CAR 17, CAR 37, CAR 0349, CAR 9549Y71 and Y72, CAR 1279 and CAR 2849 did not infringe because one or more required features, principally the necessary asymmetry or the existence of a qualifying band, were absent.

First instance judgment. The judgment records earlier proceedings in the same patent litigation, including [2013] EWPCC 3, [2014] EWCA Civ 40, [2015] EWHC 1371 (IPEC) and [2016] EWHC 815 (Ch), but this action was determined at trial on infringement.