Use of disclaimers in European Patent Applications
Historically, for applications in the chemical field, and in particular in the pharmaceutical field, disclaimers could be introduced into a claim to a generic compound in order to distinguish from prior art which disclosed a specific compound falling within the scope of the claim. A disclaimer comprised a clause added to the generic claim to exclude the specific compound mentioned in the prior art and thereby establish novelty. Such clauses were commonly in the form ".... with the proviso that when R1 is X, and R2 is Y, R3 is not Z".
Unfortunately, the validity of such practice was brought into question when a Board of Appeal of the European Patent Office (EPO) handed down a decision that the inclusion of such disclaimers during prosecution constituted added subject matter and as such was not allowable under the European Patent Convention (EPC). This not only had implications for pending applications where a disclaimer would have been a convenient way of overcoming the prior art, but also called into question the validity of a large number of granted patents.
Clarification has however now been provided in a recent decision from the Enlarged Board of Appeal. This decision sets out the limited circumstances in which a disclaimer can be used without contravening the restrictions within the EPC against added subject matter.
It is now confirmed that the addition of a disclaimer during prosecution of the application is generally allowable:
(a) if it is added to restore novelty by delimiting a claim over prior art that was published after the priority date of the application in suit but which itself has an earlier priority date. (It should be noted that it is not necessary to establish inventive step over such prior art documents;
(b) if it is added to establish novelty over an accidental anticipation in a document published prior to the priority date of the application suit. An anticipation is "accidental" if it is so unrelated and remote from the invention claimed that the skilled person would not have considered it when making the invention; and
(c) if it is added to exclude subject matter which is of a nature which is excluded from patentability.
The Enlarged Board further advised that a disclaimer should not remove more than is necessary and must meet the requirements of the EPC relating to clarity and conciseness.
Also, a disclaimer that is introduced in an attempt to establish inventive step will be considered as adding subject matter and will invalid the claim.