The term "coterminous" means to have the same boundary. In Pharma Dynamics (Pty) Ltd v Bayer Pharma AG,(1) the Supreme Court of Appeal held that a divisional patent application may have a broader or narrower protection of the inventions claimed in the parent application, but that the claims of the parent and the claims of the divisional application may not be "coterminous".
Pharma Dynamics appealed the High Court's decision to grant Bayer an interdict against them. The interdict was to stop Pharma Dynamics, through the sale of the contraceptive product Ruby, from infringing South African Patent No. 2004/4083. Patent No. 2004/4083 is a divisional patent based on South African Patent No. 2002/1668. Among other things, the Supreme Court of Appeal had to answer the question of whether Patent No. 2004/4083 is a true divisional of the parent patent, Patent No. 2002/1668.
The parent patent and the divisional patent only had one claim each. When the judge reviewed the two patents, he reviewed only Claim 1 of each patent and came to the conclusion that the two claims were not coterminous since they covered different scopes. Claim 1 of the divisional patent was broader in scope than Claim 1 of the parent patent. The Court held that a parent patent and a divisional patent have, for practical purposes, the same text, because the inventions disclosed are the same. The difference lies in their respective claims and in the variation of the text as a result of the dividing process. Further, the Court held that one of the features of the divisional system is that each divisional must have claims that are different, and the patentee cannot have the same claim in different patents.
The Pharma case does not answer the question as to whether the claims of the parent patent and the divisional patent must be viewed as a whole or individually in order to come to a conclusion as to whether the claims of the parent and divisional patent are coterminous (only Claim 1 of the parent and the divisional patent were reviewed in Pharma). This would be relevant where, for example:
- a parent patent has two claims:
- Claim 1, directed to Compound A; and
- Claim 2, directed to Compound A in combination with Compound B; and
- a divisional patent has one claim:
- Claim 1, directed to Compound A in combination with Compound B.
In this situation, the overall claims of the parent patent and divisional patent are not the same since the divisional patent does not have Claim 1 of the parent patent (the claim directed only to Compound A). However, Claim 2 of the parent patent is the same as Claim 1 of the divisional patent.
Under a broad interpretation of "coterminous" – looking at the claims as a whole – the claims of the parent and divisional patent are not coterminous in the above scenario. However, under a narrower interpretation of "coterminous" – looking at the individual claims – the claims of the parent patent and the divisional patent are coterminous in the above scenario since Claim 2 of the parent patent is the same as Claim 1 of the divisional patent. To avoid the claims of the parent patent being coterminous with the divisional patent, it would be necessary to delete Claim 2 of the parent patent if a narrower interpretation of "coterminous" were to be adopted.
Having regard to the interpretation of "coterminous" in other jurisdictions,(2) in the writer's view, it is probable that the South African courts will adopt a narrower interpretation when faced with similar facts in future. It is important to remember that the patent system is based on quid pro quo. The inventor or patentee discloses their invention to the public, and in return enjoys the fruits of their invention to the exclusion of others for a limited period. The system is designed to give the patentee enforceable rights for their invention using a patent. In other words, for one invention, one patent should be granted. If, for example, the patentee were allowed to have the same claim or claims in five different divisional patents, the patentee could arguably enforce all five divisional patents against an infringer who has a product that infringes on such claim(s). If the patentee were allowed to have the same claim in one divisional patent, by the same reasoning, they could have the same claim in as many divisional patents as they choose, depending on the importance of the claim to the patentee. This is not the object of the patent system.
Coterminous claims are not one of the nine grounds for revoking a patent in South Africa. So, what is the consequence if the claims of the parent patent are coterminous with the claims of the divisional patent? If a third party is of the view that the claims of a parent patent are coterminous with the claims of a divisional patent, the remedy would be for the third party to seek to set aside the divisional patent in a review application, as suggested in the Pharma case.
For further information on this topic please contact Christopher Mhangwane at Spoor & Fisher by telephone (+27 12 676 1111) or email ([email protected]). The Spoor & Fisher website can be accessed at www.spoor.com.
(1) Pharma Dynamics (Pty) Ltd v Bayer Pharma AG and Another, 2014 BIP 69 (SCA).
- Arbitron v Telecontrol Aktiengesellschaft  FCA 302;
- Johnstone (accessed 7 October 2021); and
- "In the Matter of Two Applications for Patents by Henry Dreyfus"  XLIV RPC 291-294.