Our services are centred around intellectual property that can be registered. We protect innovation, design, and branding across all sectors of industry, and at all stages in the supply chain.

For each IP right we offer services covering strategic advice, pre-registration searches, registrations and renewals, oppositions and dispute resolution. We handle work throughout the world, working with local colleagues in over 100 countries.


Our attorneys specialise in one or more sectors of industry, which enables them to provide quality advice with a commercial focus.

Our patent specialists have detailed understanding of the background technology, which ensures that your patent applications are prepared with the correct scope, reducing the likelihood of challenges from third parties and objections from the patent office.

They also advise whether other forms of protection would be more appropriate. Our brand specialists work with brand managers for leading brands and their advice is commercially focussed making sure that you get the best value from your budget.

G 3/14: the Enlarged Board clarifies “clarity” in opposition proceedings


In decision G 3/14, the Enlarged Board of Appeal of the European Patent Office has clarified the circumstances in which the clarity of the claims can be examined in opposition proceedings.

While lack of clarity is not a ground for opposition itself, it is established jurisprudence that clarity can be contested during opposition proceedings as an impediment to the maintenance of the patent in an amended form, provided that the problem with the clarity of a claim had “arisen out of amendments” made to the granted patent. However, interpretation of whether a problem with clarity arose “out of the amendments” has not been consistent among the boards of appeal of the EPO and both narrow and broad interpretations of the provision have been developed.

The decision of the Enlarged Board in G 3/14 confirms that the narrow approach is correct, and provides guidance on the types of amendment for which a lack of clarity might arise, and those for which no examination of clarity by the Opposition Division would be expected. In this regard, the decision will be of great importance in future to opponents and patentees considering how to conduct the opposition to their best advantage. It is also possible that the decision will affect practice during examination of the application, as both examiners and applicants will need to consider the effect that grant of a patent with unclear claims could have on prospects of successfully negotiating an opposition.

Legal Background

Article 84 EPC states that the claims of a European patent are to define the subject-matter for which patent protection is sought, and prescribes that they be clear, concise, and supported by the description. During examination of an application for a European Patent, objections to the clarity of the claims may therefore be raised by the examiner based on Article 84.

Article 100 EPC provides a finite and exhaustive list of grounds on which a granted European patent may be opposed. Lack of clarity within the meaning of Article 84 EPC is not a ground for opposition. However, Article 101(3) EPC confers on an EPO Opposition Division the power to revoke a patent where, taking into consideration the amendments made during the opposition proceedings, the patent is found to not meet the requirements of the EPC.

Because of this, the question has often been raised as to what type of amendments may trigger an examination for clarity by the Opposition Division, and when amended claims may be vulnerable to an allegation from the opponent that they lack clarity.

Over the years, two diverging schools of thought have emerged, leading to narrow and broad interpretations of the Opposition Division’s powers. According to a first line of cases, which stem from T301/87 and T227/88, during opposition proceedings objections to a lack of clarity could only be made if the alleged deficiency is a consequence of the amendments, but not if it does not arise out of the amendments themselves. The narrow interpretation thus holds that a lack of clarity is only problematic for maintenance of the patent, where it is a direct result of the amendment that has been made, and as such arose for the first time in the opposition proceedings.

By contrast, a second line of cases, which stem from T1459/05, sets out a broader interpretation and gives the Opposition Division a much broader power to examine an amended claim for clarity. Under the broader interpretation, clarity issues existing already in the wording of the granted patent, and that are brought to the attention of the Opposition Division by way of the amendment or by consideration of a piece of prior art, are also prejudicial for maintenance of the patent.

The existence of these interpretations has meant that Opposition Divisions may take different approaches to the examination of amended claims during opposition, resulting in a lack of clarity for opponents, patentees and interested third parties.

Further, it should be remembered that in the context of opposition proceedings, the original location of text, that is its location in the description, as a feature in the a dependent claim, or as a dependent claim in its entirety, can result in different expectations for the clarity and admissibility of the use of that text as an amendment.

As regards the broader interpretation of the requirements for clarity, some Boards of Appeal for example had construed the expression “arising out of” so broadly, that an amendment based solely on the combination of a granted independent claim with a granted claim would have necessitated a re-examination of clarity, and could have been challenged where the amendment, despite raising no new issues, merely brought into focus an inconsistency or ambiguity that had existed all along. This essentially gives the Opposition Division the power to examine clarity under Article 84 as if they were an examiner dealing with the application for the first time.

An extreme example of this second school of thought came in T459/09, in which it was stated that any amendment which can be regarded as being of substantial nature would, in principle, justify an unrestricted exercise of the examination power derivable from Article 101(3) EPC, including the examination of clarity, regardless of whether an amendment is based on the incorporation of a feature from the description or from the combination of claims of the granted patent. In addition, T459/09 appeared to suggest that virtually any amendment made by the patentee during opposition would have to be considered of substantial nature, since in most cases claims would be amended to include a technically meaningful feature aiming to overcome a substantive objection raised by the opponent.

A number of questions were therefore put to the Enlarged Board of Appeal with the aim of clarifying the situation. In G 3/14, the Board has not only answered the questions raised in the referral, but has taken this opportunity to review the existing case law relating to the examination of clarity in opposition proceedings in its entirety.

The Enlarged Board of Appeal was invited to clarify whether the term “amendments” is to be understood as encompassing a literal insertion of (a) elements of dependent claims as granted and/or (b) complete dependent claims as granted into an independent claim, and whether opposition divisions and boards of appeal are therefore always required by Article 101(3) EPC to substantially examine the clarity of independent claims thus amended during the proceedings. In addition, the Enlarged Board of Appeal was invited to indicate the conditions to be applied in deciding whether or not, in a given case, clarity should effectively be examined.

The Decision: “Clarity” Clarified

In G 3/14 the Enlarged Board of Appeal disapproved of the broader interpretation of Article 101(3) EPC suggested by T1459/05 and T459/09, whilst approving the narrower interpretation originating from T301/87.

Thus, following G 3/14, the Opposition Division should have no power to revoke a patent on the grounds of lack of clarity where the alleged lack of clarity already existed in the granted claims, such as in the case of:

  • amended claims resulting from the literal incorporation of a complete granted dependent claim into the independent claim; and
  • amended claims resulting from the incorporation into the independent claim of an element from a dependent claim, wherein said element is disconnected from the rest of that dependent claim (e.g. selection of one or more embodiments from a list of possible alternatives).

Further, no objections to a lack of clarity should be raised in the case of:

  • the deletion of wording from a granted claim, whereby the scope of the claim is narrowed, yet which leaves a pre-existing unclear feature;
  • the deletion of an entire independent claim or of one or more dependent claims in their entirety;
  • the deletion of optional features from a granted claim.

However, examination of the clarity of an amendment by the Opposition Division is likely to be required where the amendment takes in isolation a feature from a dependent claim that is connected to the other features in the dependent claim, as such amendments may be plainly unclear, or may even broaden the protection via intermediate generalisation, or amendments based on elements from the description or drawings. Amendments based on the location in the description always require special attention.


In summary, only newly introduced clarity issues will have to be dealt with during opposition proceedings. On the other hand, any pre-existing cause for a lack of clarity will have to be tolerated, even when it is incorporated into an amended independent claim and becomes particularly relevant to the definition of the scope of protection. In this respect, it will be interesting to see whether the interpretation endorsed by G 3/14 will be followed strictly or whether minor changes to the wording of a dependent claim will perhaps be enough to enable an opponent to raise an objection for lack of clarity during opposition proceedings.

In G 3/14, the EPO has acknowledged that independent claims will always inevitably be the subject of greater scrutiny than dependent claims. However, in view of this decision, EPO Examining Divisions may begin to examine dependent claims more thoroughly, in an attempt to prevent possible causes of lack of clarity, which may never be redressed otherwise, being included in the independent claims of a granted patent. Besides, unclear claims shall generally be construed according the broadest reasonable interpretation, and may, therefore, be more vulnerable to novelty and inventive step attacks.

There is therefore a strong incentive for applicants and for attorneys to make sure that at the drafting stage all claims, including the dependent claims, are formulated with as much consideration as the independent claims.

This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking before any action in reliance on it.

Saved Staff
Staff member

Remove all

Call +44 (0)20 7242 0901
Call +44 (0)1223 360 350
Call +49 (0) 89 206054 267
Call +(00) 31 70 800 2162
This field is for validation purposes and should be left unchanged.