Disclaimers in European Patents: Employ with Caution
By: Dale C. Hunt, PhD, and Andrew N. Merickel, PhD,
San Francisco office of Knobbe Martens Olson & Bear LLP

The claims of a patent typically define the invention in positive terms by specifying the distinguishing features of the invention. A challenge facing applicants for many patents, but particularly in the area of biotechnology and chemistry, is the situation in which it is determined after a patent application has been filed that most, but not all, of the scope of a broad claim is truly new and patentable. This situation may arise, for example, when a prior art reference is identified that discloses one of a number of compounds that are broadly claimed in the application. In this situation, the applicants would like to be able to "carve out" from their broad claims whatever small portion is not new (i.e., the compound disclosed by the prior art reference). To achieve this, applicants may wish to amend their claims to introduce a negative limitation that expressly "disclaims" or excludes particular embodiments of the invention. A typical disclaimer might read: "with the proviso that the compound is not Compound X." With the use of such a disclaimer, patent protection can be obtained for the undisclosed subject matter. However, if the disclaimer was not disclosed in the application as filed, a number of issues are raised.

In the United States, any "carve-out" must have been specifically disclosed in the specification. However, a carve-out opportunity has evolved over the last decade in European case law that does not require such a specific disclosure. A number of seemingly conflicting decisions left this body of law uncertain and in need of clarification. The confusion surrounding "disclaimer" practice prompted the referral of two cases to the Enlarged Board of Appeal of the European Patent Office ("the Board"). Two recent final decisions from the Board, published as G1/03 and G2/03, have answered many of the questions in this area. The decisions confirmed that disclaimers in patent claims may be used in certain circumstances, even when the disclaimer was not disclosed in the specification as filed. While generally well accepted by the patent community, some were disappointed that the criteria for determining the admissibility of disclaimers remains subjective. In addition, the Board found that a disclaimer is open to reassessment during the entire lifetime of the patent. As a result, a disclaimer that is considered permissible by an examiner during prosecution may subsequently be found to be impermissible for reasons that could not be predicted at the time it was submitted. Thus, some practitioners have called the newly clarified disclaimer doctrine a trap, and have urged great caution in using disclaimers in European patent prosecution.

It is important to note that a disclaiming amendment cannot be used to overcome an inventive step (i.e., obviousness) issue.

Thus, under the EPO disclaimer doctrine, a claim amendment introducing a disclaimer that is not supported in the original application is permissible in three particular circumstances. First, a disclaiming amendment can be used to restore novelty over a patent reference that was filed before, but published after, the application in which the disclaimer is being made. Such a patent reference is often referred to as a "novelty-only" reference because it cannot be applied for inventive step. Thus, a disclaimer can be used to eliminate a novelty issue arising from such a reference.

Second, a disclaimer can also be used to overcome anticipation by a more typical reference that qualifies as full prior art because it was published before the filing of the application. However, in this circumstance a disclaimer is only effective if the anticipation was "accidental." Typically, such accidental anticipation occurs in the context of a disclosure in an unrelated technical field. In its recent decision the Board clarified that an "accidental anticipation" is one that was so unrelated and remote that the inventor never would have taken that reference into account when developing the invention. Some practitioners are unhappy that this definition is subjective and may be construed narrowly.

Finally, disclaimers can be used to remove subject matter from the claims that is excluded from patentability for non-technical reasons, such as because it is contrary to public order or morality. For example, a claim to a method of medical treatment may be modified to disclaim human beings, in accordance with the European prohibition on claims covering medical methods for human treatment.

On the other hand, the Board found that disclaimers cannot be used to exclude non-functional embodiments, indicating that such a disclaimer would be a technical teaching requiring support in the original disclosure. In addition, a disclaimer must be drafted so that it does not remove more than is necessary to restore patentability or to remove unpatentable subject matter. Importantly, a disclaimer does not affect the ability to claim priority from an earlier-filed foreign application.

Thus the recent decisions of the Board confirmed that negative limitations added to claims in order to avoid anticipation are permissible in certain circumstances, and cannot be refused by the EPO for lack of written support in the original disclosure. However, it is also now clear that any amendment that is necessary to establish an inventive step for the claim must be supported by the disclosure. Further, the permissibility of a disclaimer may change based upon factors outside of the applicant's control. Thus, a disclaimer can be approved in one proceeding, such as during patent prosecution, and then be disapproved post facto in another proceeding, such as an opposition. It is this combination of rules that creates a potential trap for the unwary patent applicant.

The trap may arise in two situations. In the first, a disclaimer is used to address a reference that is an "accidental anticipation." Subsequently, a new document is identified that causes the document that was once considered an accidental anticipation to be relevant to inventive step. In such a circumstance, the disclaimer will then be considered to add technical subject matter in violation of Article 123(2), which prohibits addition of new matter not supported by the original application. In the second situation, it is determined that the claim at issue is not entitled to a claimed priority that is before the publication date but after the filing date of a prior art patent publication. As a result, the publication, which was previously only available for novelty purposes, becomes relevant to the inventive step. In both situations, a disclaimer that was once considered appropriate becomes impermissible.

If either of these situations arises during prosecution, the applicant may have the opportunity to address the prior art in a way other than through the use of a disclaimer. However, these situations are more likely to arise after the patent has been granted, in the context of an opposition. The trap about which European practitioners have warned arises from the fact that in an opposition proceeding, the scope of a claim cannot be broadened (Article 123(3)). The removal of a negative limitation from a claim, by definition, broadens the claim. Thus, if the patent is found during opposition to contain an impermissible disclaimer, the defect cannot be repaired: the disclaimer is improper because it adds new matter, but removing the disclaimer would broaden the claim. The result is revocation of the patent.

Consider a situation in which a patent applicant believes she has discovered a completely new class of molecules that are useful in treatment of disease X, the class being unified by properties not previously recognized. Since competition is rapid and fierce, she files an early application that describes the class of molecules broadly and provides those few working examples that are available at the time. Years later, while prosecuting the broad composition claims in Europe, a prior art reference is cited in which one molecule that is arguably a member of the class is described. However, the reference is in the completely unrelated field of thin film deposition. Under the European disclaimer rules, this could be considered an "accidental anticipation" and the applicant would be permitted to add a negative limitation to her claims, excluding the disclosed molecule and thus avoiding the reference.

A patent thereafter issues with a claim that includes the disclaimer, and a competitor files an opposition. In the opposition, a reference is produced indicating that a group of molecules known for thin film deposition may be useful in treating some diseases (without specifying disease X). The question then arises whether or not the reference which the disclaimer addressed is one that is so unrelated and remote that the inventor never would have taken that reference into account when developing the invention. While both sides can argue their respective positions, if the accidental anticipation rule is interpreted narrowly and the reference is found to be a non-accidental anticipation or to show lack of an inventive step, the applicant finds herself trapped in a position in which she cannot remove an impermissible disclaimer. The result is the revocation of her patent.

While disclaimers are an appealing way to avoid certain types of prior art in the prosecution of European patents, the criteria for determining the permissibility of such disclaimers is subjective. Further, the permissibility of the disclaimers can change over the term of a patent and could potentially lead to revocation of the patent. As a result, practitioners should be cautious about the use of disclaimers and should consider alternative ways of overcoming prior art in order to ensure that some coverage is maintained in the event a disclaimer is later found impermissible. Likewise, applicants who choose to use disclaimers to maximize claim breadth would be well advised to file a divisional application to pursue claims that do not require a disclaimer for patentability.

Knobbe Martens Olson & Bear LLP is California's largest intellectual property law firm and is consistently rated among the top firms nationally for litigation and prosecution of patents and trademarks. Knobbe Martens has offices in San Francisco, Orange County, San Diego, Los Angeles, Riverside, and San Luis Obispo.

Note: The authors would like to thank their European colleagues, particularly the attorneys of Sternagel Fleischer Godemeyer Polypatent, for helpful analysis of the Board decision, and their partners Dan Altman and Karoline Delaney for their advice on this article.