Nu-World Industries (Pty) Ltd v Strix Limited

Strix Limited is the holder of South African patent 95/4779 relating to thermally sensitive overheat controls (cut-out switches) used in domestic kettles. Nu-World Industries imported and sold kettles allegedly containing infringing controls. Strix sued Nu-World in the Court of the Commissioner of Patents for patent infringement. The issues were separated, with the court first determining infringement. Ultimately, on appeal, the Supreme Court of Appeal found that three specific controls (Liang Ji LJ-06A, Liang Ji LJ-06 and Sunlight SLD-105A IL) infringed the patent, while a fourth did not. An interdict and an enquiry into damages or a reasonable royalty were ordered. Thereafter, Strix sought to amend its pleadings in the damages phase to include additional and modified controls not determined in the infringement phase. Nu-World objected, contending that it was impermissible to introduce new alleged infringements after the infringement issue had been finally decided.

The appeal was upheld with costs. The order of the Court of the Commissioner of Patents was set aside and replaced with an order granting only paragraphs 3, 4 and 5 of the application to amend, and dismissing the remainder of the amendment application with costs.

This case clarifies the limits of damages and royalty enquiries following a separated determination of patent infringement. It affirms the principle of finality in respect of separated issues and confirms that new alleged infringements cannot be introduced at the damages stage. The judgment also provides important guidance on the interpretation of court orders, particularly distinguishing between forward-looking interdictory relief and backward-looking damages claims in patent litigation.