Merck Sharpe Dohme Group v Cipla Agrimed (Pty) Ltd

The appellants (Merck Sharpe Dohme Corp and Merial LLC) were joint patentees of South African Patent 98/10975 (the 98 patent) which claimed a long-acting injectable formulation for treating parasites. The formulation comprised: (a) a therapeutic agent; (b) hydrogenated castor oil; and (c) a specific combination of hydrophobic carriers. The priority dates of the 98 patent were 3 December 1997 and 7 May 1998. The respondent (Cipla Agrimed) applied to revoke the patent on grounds of lack of novelty. The respondent relied on the appellants' own earlier patent specification 92/7457 (the 92 patent), which was made available to the public on 30 March 1993, as prior art. The 92 patent disclosed an injectable formulation comprising hydrogenated castor oil, an avermectin compound, and a hydrophobic carrier. The 92 patent taught that "any physiologically and pharmaceutically acceptable carrier may be used so long as the avermectin compound is soluble therein" and listed examples including triacetin, distilled acetylated monoglycerides, miglyol 812, and safflower seed oil. The only individualised description in the 92 patent was of Triacetin alone as the preferred carrier. The Commissioner of Patents (Teffo J) held that all claims of the 98 patent were anticipated by the 92 patent and revoked the patent. The patentees appealed.

• Whether the 98 patent was anticipated by the prior art disclosed in the 92 patent and therefore invalid for lack of novelty
• The proper test for anticipation: whether the prior art discloses and enables the invention claimed
• Whether a generalised description of a class in prior art necessarily discloses each specific member of that class
• The approach to be adopted when considering the validity of a selection patent
• Whether the prior art provided clear and unmistakable directions to perform the invention claimed in the 98 patent

1. The appeal is upheld with costs, including the costs of two counsel. 2. The order of the court below is replaced with the following: (a) The application for revocation of South African Patent Number 1998/10975 is dismissed. (b) Each of the claims of South African Patent Number 1998/10975 is certified as being valid in terms of section 74 of the Patents Act No 57 of 1978. (c) Costs are awarded to the joint patentees, including the costs of two counsel.

For prior art to anticipate a patent claim and render it invalid for lack of novelty: (1) There must be prior disclosure: the prior art must disclose subject matter which, if performed, would necessarily result in an infringement of the patent. Disclosure of a generalised class does not necessarily amount to disclosure of each specific member of that class - an "individualised description" of the claimed invention is required. (2) There must be enablement: the ordinary skilled person must be able to perform the invention based on the prior disclosure without significant ingenuity or experimentation. The test for enablement in anticipation is the same as the test for sufficiency of disclosure. Both disclosure and enablement are distinct requirements, each with its own function, and both must be satisfied. The prior art must contain "clear and unmistakable directions" to do what the patentee claims to have invented. If something remains to be ascertained which is necessary for the useful application of the discovery, there is sufficient room for another valid patent. If carrying out the prior art would not necessarily result in infringement of the later patent, the later patent is not anticipated. Selection patents are not to be treated as a special category of patent requiring different treatment from other patents when determining validity.

The Court observed that a patent represents a quid pro quo: the monopoly conferred upon the patentee in exchange for new knowledge presented to the public which will be available for general use after the patent expires. The function of the claim is to inform prospective rivals of the limits of the field denied to them while the patent lasts, and the function of the body of the specification is to instruct the public how to carry out the invention when the field is eventually open. The Court noted the practical differences between low-tech and high-tech inventions: in low-tech cases, simple disclosure may be enough to enable performance, while in high-tech pharmaceutical cases, bald assertion of the invention's existence may need to be accompanied by detailed disclosure enabling the skilled person to perform it. The Court cited with approval the analogy from Dr Reddy's Laboratories: "Where does a wise man hide a leaf? In a forest... it is, at least faintly, ridiculous to say that a particular leaf has been made available to you by telling you that it is in Sherwood Forest. Once identified, you can of course see it. But if not identified you know only the generality: that Sherwood Forest has millions of leaves." The Court noted that elements of pharmaceutical formulations, including active pharmaceutical ingredients, react with each other and in the animal body (in vivo) in wholly unpredictable ways, which affects what can be said to be disclosed or enabled by prior art. The Court observed that the very significant advantages (duration of activity up to 180 days versus 42 days) of the patented formulation over the prior art formulation demonstrated that the patent represented a significant technical advance.

This case is significant for clarifying and developing South African patent law on anticipation and novelty, particularly in relation to selection patents and chemical formulations. The judgment adopts and applies the modern two-step approach to anticipation from UK jurisprudence (Synthon), requiring both disclosure and enablement. It confirms that these are distinct requirements, each with its own function, and both must be satisfied. The case rejects the outdated proposition that disclosure of a broad class necessarily discloses each specific member of that class. It clarifies that an "individualised description" is required for anticipation, not merely a general description within which the claimed invention might theoretically fall. The judgment confirms that selection patents are no longer to be treated as a special category requiring different treatment, following Dr Reddy's Laboratories. The case provides important guidance on how to assess whether prior art provides "clear and unmistakable directions" to perform the claimed invention. It emphasizes that if "something remains to be ascertained which is necessary for the useful application of the discovery," there is sufficient room for another valid patent. The decision also clarifies that the test for enablement in anticipation is the same as the test for sufficiency, producing symmetry in patent law. The case is particularly important for pharmaceutical and chemical patents where formulations and combinations of compounds are claimed.