Kohler Mira Ltd v Norcros Group (Holdings) Ltd [2025] EWCA Civ 1670 (22 December 2025)

Kohler Mira Ltd v Norcros Group (Holdings) Ltd [2025] EWCA Civ 1670 (22 December 2025)

The phrase 'the diverter valve is configured so that flow rate is substantially unchanged during changeover' requires the diverter valve, alone or in combination with other components of the instantaneous water heater, to achieve the specified result. The term 'substantially unchanged' is not defined in the patent,...

Source-derived case information.

Citation
[2025] EWCA Civ 1670
Parties
Claimant/respondent: Kohler Mira Limited; Defendant/appellant: Norcros Group (Holdings) Limited
Jurisdiction
England and Wales
Judgment Date
22 December 2025
Procedural Posture
Patent Infringement Appeal / Court of Appeal Judgment
Outcome
Appeal allowed; patent revoked for insufficiency; no infringement found.
Legal Topics
Patent Infringement, Claim Construction, Sufficiency, Uncertainty in Patent Claims, Doctrine of Equivalents
Intellectual Property Patent Law Patent Infringement Claim Construction Sufficiency Uncertainty in Patent Claims Doctrine of Equivalents

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Parties

Kohler Mira Limited

Claimant/respondent

Norcros Group (Holdings) Limited

Defendant/appellant

Procedural Posture

Patent Infringement Appeal / Court of Appeal Judgment

Legal Issues

  1. 1 Proper construction of claim 1 of UK Patent No. 2466504, specifically the meaning of 'the diverter valve is configured so that flow rate is substantially unchanged during changeover'
  2. 2 Whether Triton's DuElec range infringes claims 1 and 4 of the Patent
  3. 3 Whether the claims are invalid for uncertainty (insufficiency)

Ratio Decidendi

The phrase 'the diverter valve is configured so that flow rate is substantially unchanged during changeover' requires the diverter valve, alone or in combination with other components of the instantaneous water heater, to achieve the specified result. The term 'substantially unchanged' is not defined in the patent, and the only criterion proposed (risk of scalding) is not applicable to all uses covered by the claim. As no ascertainable criterion exists, the claim is insufficient for uncertainty, and the patent is invalid. Triton's products do not infringe as the relevant result is achieved by other system components, not the diverter valve.

Court Disposition

Appeal allowed; patent revoked for insufficiency; no infringement found.

Orders

  • Patent revoked for insufficiency under section 72(1)(c) of the Patents Act 1977
  • No finding of infringement against Triton