Monsanto Company v MDB Animal Health (Proprietary) Ltd

Monsanto Company was the holder of South African Patent No 85/7642 entitled “Prolonged release of biologically active polypeptides”. The patent claimed, inter alia, a substantially non-aqueous injectable composition for parenteral administration comprising bovine somatotropin in a continuous phase of a biocompatible oil. MDB Animal Health (Pty) Ltd imported and sold an injectable product known as “Hilac”, consisting of bovine somatotropin formulated with alpha tocopherol acetate (synthetic Vitamin E). The central dispute was whether Vitamin E fell within the meaning of “oil” as used in the patent claims. If it did, infringement of claims 1, 2, 4 and 5 was common cause. The court a quo (the Commissioner of Patents) held that Vitamin E was not an oil for purposes of the patent and dismissed Monsanto’s infringement claim, prompting this appeal.

The appeal was upheld with costs. The order of the court a quo was set aside and replaced with a declaratory order that the respondent, by importing and selling “Hilac”, infringed claims 1, 2, 4 and 5 of SA Patent 85/7642. The respondent was ordered to pay the costs relating to the infringement claim. Final relief such as an interdict and damages was deferred pending the outcome of the respondent’s postponed counterclaim for revocation of the patent.

The case is a leading South African authority on patent claim interpretation, particularly the distinction between limiting definitions and preferred embodiments in a patent specification. It confirms that patent claims should not be narrowly construed by reference to selected passages read in isolation, and that functional and contextual interpretation is central in infringement analysis. The judgment is frequently cited for its clear restatement of interpretive principles in patent law.