Nested claims before the EPO: pragmatic cosmetics or clarity-obstructing nuisance?

It has been said that the logo of the European Patent Office (EPO) resembles the ideal method for drafting a set of patent claims: the broadest, most well-rounded claim should be in the centre, surrounded by additional layers of protection in the form of dependent claims. This can result in nested subject matter within the scope of the broadest claim. The result could be a set of nested claims – or could it?

The EPO Examining Division is not always keen to accept nested claims. In fact, over the years claims featuring nested ranges have often encountered objections based on an alleged lack of clarity. In such cases, for example, a single claim would recite a broad range, but preferably a smaller range, and ideally an even smaller range. An illustration is the following liberal translation (from German) of the second claim of European Patent Application 05785721.1: 

"2. Mouth and tooth care and cleaning agent according to claim 1, characterized in that it comprises from 12 to 60 wt.%, preferably 15 to 50 wt.%, more preferably 17 to 40 wt.%, and most preferably 20 to 35 wt.% sorbitol."

To clarify that this is a prime example of a nested claim, the elements can be spatially rearranged as follows:

  • "2. Mouth and tooth care and cleaning composition according to claim 1, characterized in that it comprises from";
  • "12 to 60 wt.%";
  • "preferably 15 to 50 wt.%";
  • "more preferably 17 to 40 wt.%"; and
  • "most preferably 20 to 35 wt.% sorbitol".

The ranges recited in the claim start at the widest range, and progressively smaller central swaths funnel closer to the ideal composition.

The patent application containing this nested claim was rejected by the Examining Division on the grounds of a lack of clarity and conciseness in the nested claim. As such, the claim was said to violate Article 84 of the European Patent Convention, as well as Rules 43(3) and 43(4), without further substantiation.

Article 84 of the convention requires claims to be both clear and concise, and to be supported by the description. Rule 43(3) allows (rather than requires) a claim that states essential features of an invention to be followed by dependent claims concerning particular embodiments of that invention. Rule 43(4) relates to how dependent claims should be worded or grouped, requiring this to be done "in the most appropriate way possible". In a sense, Rule 43(4) merely provides best practice instructions on how to present information. 

The applicant appealed and at the oral proceedings argued that Rule 43(3) merely provides an option, but does not require independent claims to be followed by dependent claims. In addition, the Examining Division had not made clear which ambiguity would result from the wording of claim 2, let alone whether such a lack of clarity would hinder a reader in interpreting the scope of the claim. In connection to this, the applicant quoted the guidelines for examination (C-III, 4.9 – F-IV, 4.9):

"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 Technical Board of Appeal agreed with this argument (Decision T 1882/12) on the following grounds. The claim as presented was a nested claim where optional limitations neatly fell within the broadest limitation. Rule 43(4) allows dependent claims to exist, but does not force them to exist. Rule 43(4) advises only on how dependent claims should be presented. As such, the rule was irrelevant to the alleged lack of clarity.

The board then discussed the guidelines for examination and concluded that they call only for careful examination of preferred features. As a result, the guidelines implicitly allow the actual use of preferred features, provided that they do not introduce a lack of clarity. It followed that nested claim 2 did not conflict with the rules regarding clarity and thus could not be considered unclear only because it contained non-limiting information.

However, the board noted that the preferred embodiments might as well have been presented as dependent claims, instead of in their current form. Nevertheless, in the case at hand the amount and presentation of the nested embodiments were deemed to be acceptable and the claims were held to be understandable without requiring excessive analysis.

The expansion of these preferred embodiments into dependent claims would have entailed high claims fees. Thus, it is unsurprising that the applicant wished to maintain the claim in its nested form.

Having established that the claims were at least not unclear, the second requirement of Article 84 of the convention – conciseness – was considered. Could the Examining Division have had a point in citing Article 84 against a claim with so much non-limiting information in it? The board disagreed: the nested subranges served the express purpose of providing potential fallback positions for the applicant. Thus, they could not be considered superfluous per se, even while they were not limiting to the claim.

Therefore, the claim was deemed to be sufficiently concise because there was no information without an identified function, and the nested claim was thus found to be acceptable. However, a word of caution regarding national jurisdictions: while this part of the ruling holds true for prosecution before the EPO and appears to favour embedded preferred embodiments over dependent claims, not all national jurisdictions provide the option to amend individual claims. Such jurisdictions allow only full maintenance or full deletion during national proceedings. Thus, fallback positions that are embedded within a claim are not always fallback positions, and there is still a case to be made for independent claims.

The Technical Board of Appeal overturned the Examining Division's decision to reject the patent for a lack of clarity. It is hoped that this decision will become a useful tool for European patent attorneys confronted with objections based on Article 84 or Rules 43(3) or 43(4) aimed at claims that feature optional embodiments. However, the board warned that despite the fact that no formal objections against optional matter exist, not all claims featuring optional matter are automatically clear and concise. It is an intriguing thought that the presentation of a claim, while not influencing its actual scope, might influence its allowability. Therefore, when drafting nested claims, it is wise to ensure that they are as well ordered or as progressive as possible, much like claim 2 in the case at hand. Fortunately, the EPO logo implicitly hints that perfect symmetry is not required.

This is an Insight article, written by a selected partner as part of IAM's co-published content. Read more on Insight

Unlock unlimited access to all IAM content