Don’t fall into an indefensible opposition trap – you can use a routine pre-grant patent check in Europe

Many European patent applications are prosecuted through to grant where through determined and persuasive argument, luck, or an Examiner oversight, a claim is agreed for grant with a ‘questionable’ limiting feature amendment. Unfortunately, in some cases the long and arduous quest to achieve a successful granted claim often involves multiple stake holders (applicants and licensees, their attorneys, and the European representative attorneys); extends over several years, squeezing through tight deadlines, which can lead to the loss of sight on the eventual quality of the granted claim, regardless of the Examiner’s agreement on allowability.

Seasoned patent prosecutors and applicants will be aware of the strict European added subject matter rules under Art. 123(2) EPC, whereby “The European patent application or European patent may not be amended in such a way that it contains subject-matter which extends beyond the content of the application as filed”.

European patent prosecution frequently re-visits this rule during the process of submitting amendments to the claims. There can often be an argument regarding the basis/support for an amendment when the proposed amendment is not explicitly found in the application as filed, especially in the case of applications originating from overseas that have not been drafted with the strict rules and practice in Europe in mind. In some cases, claims are amended early in prosecution, such as upon European Regional Phase entry or the filing of a divisional application, where the new claims differ from the original as-filed claims. Sometimes, there is simply no mention or objection regarding the amendments, and the claim set continues its march to grant.

However, Article 123(3) EPC is a further fundamental rule that comes into consideration in a post-grant opposition in Europe. This article requires that “The European patent may not be amended in such a way as to extend the protection it confers”.

The result of this rule can be an unescapable trap. Following a finding of added subject matter, the Patentee must amend the offending claim to remove the added subject matter, or the patent is revoked. Yet, they cannot remove a limiting feature, if it results in an unallowable broadening of the scope. There is often no remedy, unless the ‘questionable’ added feature can be further limited to something which has clear basis.

So called ‘intermediate generalisations’ are often a cause for added subject matter issues falling into the trap, where a claim feature has been taken out of an example, which is specific to and in context with all the features of that example, and generally applied to the broad claim scope. There may be no basis to do this, but it is now part of the granted claim. It can’t be removed during opposition if this broadens the claim scope. The only remedy would be to limit the entire claim to follow the same scope of the example from which it was extracted. This will likely result in a claim that is so narrowly focused in scope, it is of no practical use to prevent infringement.

Squeezing in such a ‘questionable’ limiting feature into an independent claim may be possible during examination of the application, but it can be indefensible and result in complete revocation of the patent in a post-grant opposition. In the absence of knock-out prior art, it is often considered to be the most effective and straightforward attack an opponent can make when faced with such a claim set. Surely it’s much better to avoid allowing any opponent to exploit this potential advantage at the post-grant stage.

Of course, being aware of this issue during every act of pre-grant amendment can help to prevent future opposition problems. However, a more routine check can be built into your European prosecution, which can help to prevent losing sight of this in the fog of the arguments and amendments during examination. A recommended course of action would be to routinely commission a specific review for added subject matter in the independent claims (e.g. build a basis table for all the independent claim features) at the stage of a Notice of Allowance under Rule 71(3) EPC (a review of the Druckexemplar text). Whilst it may add an additional cost for review, it could save or warn the applicant of any risk for an indefensible opposition.

For example, if a ‘questionable’ limiting feature amendment is identified in the pre-grant review, the applicant can decide to: proceed to grant with awareness of the risk; reject the allowable text and amending the claims further – which will most likely result in re-entering the substantive examination procedure; and/or file a divisional application, such that there is still a chance to prosecute some allowable claims without the troublesome amendment, even if the granted claim of the parent patent goes on to be opposed and revoked.

Here at Barker Brettell LLP we can advise on this risk. If you would like to routinely initiate a review upon receiving a Notice of Allowance Rule 71(3) EPC, or even earlier in the prosecution process, then please contact the author or your usual Barker Brettell European Representative.

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