Optional features in a patent claim

March 23rd, 2016

By Yogani Naicker

In patent law, the claims of the patent define the scope of protection afforded to a patentee, and for this reason the claims must ‘define with clarity and precision the scope of the invention claimed as a monopoly’ (Gentiruco AG v Firestone SA (Pty) Ltd 1972 (1) SA 589 (A)). Certain words give particular problems when used in patent claims and one of these is the word ‘preferably’ and similar words and phrases. A matter involving use of these terms recently came before the Board of Appeal (the board) of the European Patent Office (EPO), T 1882/12 (www.epo.org), which may change the approach when interpreting features introduced by these terms in a patent claim.

Before proceeding to the facts of the case it may be useful to give a bit of background. In Europe, excess claim fee charges are applicable if a patent application includes more than 15 claims; such excess claim fee charges have resulted in the practice of combining multiple integers into a single claim simply to avoid this additional cost.

The patent applicant in this case followed the same approach to avoid the additional cost. Claim 2 of the application, which was used as an example by the board, reads:

‘2. A mouth and tooth care and purification agent according to claim 1, characterized in that it contains 12 to 60 wt.-%, preferably 15 to 50 wt.-%, more preferably 17 to 40 wt.-% and particularly 20 to 35 wt.-% of sorbitol and/or glycerol and/or 1,2 propylene glycol’ (my italics).’

The question that arose is whether claim 2 contravened the requirements of clarity and conciseness in terms of art 84 of the European Patent Convention by the use of the terms ‘preferably’ and ‘particularly’. The Examining Division found that claim 2 did contravene art 84 and rejected the claims. Reference was made to the Guidelines for Examination in the EPO (documents.epo.org) for optional features, which reads:

‘4.9 Optional features

Expressions like “preferably”, “for example”, “such as” or “more particularly” should be looked at carefully to ensure that they do not introduce ambiguity. Expressions of this kind have no limiting effect on the scope of a claim; that is to say, the feature following any such expression is to be regarded as entirely optional.’

The applicant appealed the decision of the Examining Division and the matter was heard before the board. The board stated that even though the guidelines provide that the feature following the expression is regarded as optional, the expression must still be examined carefully in order to determine whether any confusion may be created. If the expression creates confusion, this means that there is ambiguity of the subject matter for which protection is sought, resulting in a lack of clarity. Further the board rejected the Examining Division’s arguments that the claims were not concise and contained superfluous, non-limiting features.

The board reasoned that if claim 2 was carefully examined, the broadest range of 12 to 60 wt. % was defined. The preferred embodiments were confined within this broadest range. Further as these confined ranges remained within the parameters of the broadest range, this consequently created a relationship between the broadest range and the preferred embodiments. The board, as a result of this finding, concluded that the preferred embodiments did not create a lack of clarity. The board stated that the optional expressions will not in all circumstances lead to a lack of clarity, but careful examination on a case by case basis must be performed.

The question then arises as to the relevance of this decision in South African law. In South Africa there are no excess claim fee charges, and therefore there is no need to use ‘preferably’ for this particular purpose. However, in South African law claims must be clear, and any patent, that contains a claim that is unclear is liable for revocation in terms of s 61(1)(f) of the Patents Act 57 of 1978.

There has only been one case on this issue in South Africa, viz Ian Fraser-Johnson v GI Marketing CC 1993 BP 461 (CP).

Again the objection was a lack of clarity of claim 2, which read:

‘An arrangement as claimed in claim 1 wherein a cover is preferably provided to permit the airflow to and from the valve but still to prevent the ingress of leaves or dirt which could have a detrimental effect upon the working of the valve’ (my italics).

The judge stated that:

‘Claim 2 of the 1987 patent was attacked on the ground that it is ambiguous. The scapegoat is the word “preferably”. There is merit in this contention. As the claim stands it is not clear whether the claim has a cover as an integer or whether it has not. If it has not, claim 2 does not differ from claim 1 and is mere surplusage. If it has a cover, why is this requirement watered down by the use of the word “preferably”?

I hold that claim 2 of the 1987 patent is ambiguous.’ 

In other words the court questioned the reason for introducing an integer in a claim by the term ‘preferably’ if it did not add value to the invention. If this integer was important to the invention, it should simply be claimed with certainty so that third parties would clearly understand the key features or integers of the invention. Although the structure of this claim differed from that of the claim in issue in the European case, we can conclude that in South Africa, the use of the term ‘preferably’ may lead to a lack of clarity. However, our courts may be influenced in the future by this recent European judgment, and come to a different view.

Yogani Naicker BSc Chemical Engineering (UKZN) is a candidate attorney at Spoor & Fisher in Pretoria.

This article was first published in De Rebus in 2016 (April) DR 48.

De Rebus