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The enlarged board of appeal adds clarity

2 April 2015

The Enlarged Board of Appeal has recently given guidance on the extent to which amendments should be examined for clarity in EPO opposition proceedings in its decision G 3/14 (see here). In a decision that will be welcomed by patent proprietors (but not opponents), the Enlarged Board decided that the clarity of an amendment to the claims can be examined only to the extent that the amendment introduces a possible lack of clarity.

Although lack of clarity is not a ground of opposition in the EPO, in most opposition cases patent proprietors seek to make claim amendments in order to save the patent from revocation. In those circumstances, an Opposition Division is obliged to consider whether, once amended, the patent meets the requirements of the European Patent Convention more generally. The question addressed by the Enlarged Board of Appeal was the extent to which Opposition Divisions should actively examine clarity of the patent when amendments are made.

Over the years different Technical Boards of Appeal have given guidance on this topic and diverging lines of case law have emerged. According to one line of case law (exemplified by the seminal Biogen “Alpha Interferon decision” T 301/87), objections for lack of clarity could not be raised unless the amendment itself introduced the lack of clarity. According to another line (exemplified by T 459/09), any amendment opened the door to a full analysis of clarity.

In the present case, the patent proprietor wished to amend granted claim 1 by incorporating the text of a granted dependent claim in which there was a possible lack of clarity due to the use of the term “substantially”. By adopting the different lines of case law on this topic, either the amended claim would have to be accepted as it is, regardless of any lack of clarity, or the claim language would have to be examined for clarity (and potentially refused).

In coming to a decision, the Enlarged Board of Appeal followed the reasoning of the Board of Appeal in T301/87 and decided that the clarity of an amendment to the claims has to be examined only to the extent that the amendment introduces a possible lack of clarity. In the particular circumstances of this case, a combination of claims as granted cannot be examined for clarity in opposition proceedings.

Of practical relevance, the examination of claims during opposition proceedings will be significantly limited by this decision. Those who are concerned by unclear claims in pending competitor European patent applications should consider filing third party observations commenting on clarity (anonymously, if desired), rather than waiting for opposition proceedings. The Enlarged Board’s decision is also likely to put pressure on the EPO Examining Divisions to consider more carefully the clarity of dependent claims.


John Dean and Chris Hall
Life Sciences & Chemistry group and Electronics, Computing & Physics group

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This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.

© Withers & Rogers LLP, April 2015