Following an infringement action between the parties, the Court of Appeal had held the Claimant’s patent valid and infringed and made an order for damages, an injunction and a series of undertakings. Subsequently, however, the Technical Board of Appeal of the European Patent Office (EPO) found that the claims of the patent in suit were invalid. The EPO did proceed to allow amended claims.

The Defendant applied to the Court of Appeal for a variation of that Court’s earlier judgment, on the ground that the amendment of the patent (which has retrospective effect) operated to prevent the Claimant from enforcing the order.  

The Claimant consented to the discharge of the injunction, acknowledging that it could no longer rely upon the injunction in the order to prevent further acts of infringement in relation to the amended claims. However, it reserved its position in respect of the other parts of the order and, in particular, the order for an inquiry as to damages.  

The Court of Appeal dismissed the Defendant’s application to discharge the order in relation to the inquiry for damages and for the repayment of damages already paid. Whilst there was authority for the proposition that the Court would not enforce an injunction obtained prior to the amendment as a means of preventing future infringements of the amended patent, this did not mean that an amendment also had the effect of preventing the successful patentee from enforcing the judgment for damages which had been obtained in respect of the acts of infringement in relation to the unamended patent.  

The inquiry as to damages was not an attempt to enforce a new claim, but was merely the quantification of the amount payable under an already perfected judgment. It was not open to the Defendant to argue that the estoppel created by that judgment should not be enforced, given the subsequent amendment or revocation of the patent.  

The Court also rejected the Defendant’s submission that it should be released from the undertaking to pay damages in respect of the remaining part of a customer’s order which had been the subject of a carve-out from the injunction and which remained unfulfilled at the time of the Court of Appeal’s order. The enforcement of the undertaking depended not on the continued existence of the injunction, but on whether the Claimant remained entitled to damages in these proceedings for the sale and delivery of the relevant items.