Cartonneries De Thulin SA v CTP White Knight Ltd

A patent claim must be construed as a whole, balancing fair protection for the patentee with reasonable certainty for third parties. The claims define the monopoly, and the specification cannot impose a limitation which the claim does not express or properly imply. A functional requirement may leave a range of possible dimensions without creating a precise numerical limit. The statutory test for obviousness remains objective and must be assessed without hindsight, with appropriate appellate caution. Added matter is established by comparing the disclosure in the application as filed with the disclosure in the patent as granted. Matter which is not clearly and unambiguously disclosed, expressly or implicitly, in the application cannot be added by amendment.

Carthuplas sued White Knight for infringement of a patent concerning a two-disc compact-disc storage cassette. Neuberger J held that the patent was valid but that White Knight’s products did not infringe. He dismissed White Knight’s revocation counterclaim.

Carthuplas appealed on construction and infringement. White Knight cross-appealed on validity, relying on obviousness and added matter under the Patents Act 1977. The central issues were whether claim 1 contained an implied numerical maximum pivoting angle, whether the invention was obvious, and whether the claim introduced matter absent from the application as filed.

1. Construction and infringement. The appeal on construction was allowed. Claim 1 did not contain an implied numerical maximum pivoting angle of about 130° or 135°. Claim 7 expressly specified a maximum angle, whereas claim 1 specified only a minimum angle and a functional end position. The requirement that both sides of the disc-holding part be freely accessible imposed a functional limitation, but did not create a maximum below 180°. White Knight’s products, opening through about 180°, would therefore have infringed if the patent had been valid.
2. The claims had to be read in the context of the specification and the European patent framework, but the specification could not be used to introduce a limitation absent from the claim. The construction had to reconcile the language of the claims with the technical and commercial context, providing fair protection and reasonable certainty.
3. Obviousness. The cross-appeal on obviousness was dismissed. The statutory inquiry under the Patents Act 1977 was objective. The court accepted the guidance in Windsurfing International v Tabur Marine and the need to avoid hindsight. Despite the different construction adopted on appeal, the trial judge was entitled to accept the expert evidence that the separate hinge arrangement and pivoting-travel limiter involved an inventive step. The court would not substitute its own evaluation where the issue was one of degree and no legal principle had been misunderstood.
4. Added matter. The cross-appeal succeeded on the added-matter ground. Under sections 72(1)(d) and 130(3), the relevant comparison was between what the skilled person would understand to be disclosed in the application as filed and what was disclosed in the patent as granted. The addition of the requirement that both sides of the disc-holding part be freely accessible was an important functional element of the claim. It was not clearly or implicitly disclosed in the original application. The patent was therefore invalid and was ordered to be revoked.
5. The cross-appeal was allowed and the patent revoked. White Knight was ordered to pay half of Carthuplas’s costs. Permission to appeal to the House of Lords was refused, subject to the stay and undertaking recorded in the order.

• Court of Appeal (Civil Division): Allowed Carthuplas’s appeal on construction and infringement in principle, dismissed the obviousness challenge, allowed White Knight’s cross-appeal on added matter, and ordered revocation of the patent.
• Chancery Division: Neuberger J dismissed the infringement claim, holding the patent valid but not infringed, and dismissed White Knight’s revocation counterclaim.