Limits of a Limited Opposition

L. Walder-Hartmann (DE)

The EPC requires a statement about the extent to which a patent is opposed (R. 76 (2) (c) EPC). If it is not the entire patent that is indicated in this statement, the opposition is understood to be a limited opposition. The way in which a limited opposition influences the examination of the opposition has been determined in more detail in the decision G 9/91 of the Enlarged Board of Appeal. However, not all case constellations have been considered. The question remains where exactly the limits of a limited opposition lie and if, and under which conditions, such a limited opposition may later be extended. To answer this question, an investigation into the nature of an opposition is necessary as well as a critical review of the reasons of the decision G 9/91 in this context. This investigation is the subject of the present part A of the article. In a second part B, the results of the investigation are used to identify the limits of a limited opposition and the conditions under which they can be pushed.

I. Introduction

It is common understanding that the European Patent Convention (EPC) does not only allow for an opposition to be filed against the patent as a whole, but also allows – in a sense to be discussed – for an opposition of limited extent. The possibility to limit the extent of the opposition is derived from Rule 76 (2) (c) EPC which states that the notice of opposition shall contain, inter alia, a statement of the extent to which the European patent is opposed. The European Patent Office (EPO) form for filing an opposition contains fields to indicate whether the opposition is filed against the patent as a whole or only against certain claims to be specified by their numbers.

The function and implications of Rule 76 (2) (c) EPC have been debated. Some held Rule 76 (2) (c) EPC to be relevant only for the assessment of the admissibility of the opposition as set forth in Rule 77 (1) EPC,[1] but not relevant for the examination of the opposition in accordance with Art. 101 (1) EPC.[2] According to this position, the power of an Opposition Division[3] to examine the opposition would always have extended to the patent as a whole. It is a different question if, in view of Art. 114 (1) EPC, the Opposition Division would then have had the obligation to always examine the patent as a whole or if the extent indicated in the notice of opposition would have limited the obligation albeit not the power to examine. Others saw Rule 76 (2) (c) EPC to fulfill a double function, namely not only for the admissibility of the opposition, but also for substantive examination. This is the view endorsed by the Enlarged Board of Appeal in the decision G 9/91, stating that the extent to which the patent is opposed according to Rule 76 (2) (c) EPC sets the legal and factual framework within which the substantive examination shall be conducted in principle.[4]

The Enlarged Board of Appeal ruled in the decision G 9/91 that the power of an Opposition Division to examine and decide on the maintenance of a European patent under Article 101 (1) and (2) EPC (previously Articles 101(1) and 102 EPC’73) depends upon the extent to which the patent is opposed in the notice of opposition pursuant to Rule 76 (2) (c) EPC (previously Rule 55 (c) EPC’73). Further, the Enlarged Board of Appeal ordered that subject-matters of claims depending on an independent claim which falls in opposition or appeal proceedings may be examined as to their patentability even if they have not been explicitly opposed provided their validity is prima facie in doubt on the basis of already available information.[5]

The second part of this order of the Enlarged Board of Appeal already makes it clear that the extent to which the patent is opposed does not in itself constitute a formal and therefore absolute barrier for substantive examination. A first question is therefore how far the duty and power to examine goes if an opposition of limited extent according to Rule 76 (2) (c) EPC has been filed, and particularly if the decision G 9/91 holds a final answer to this question. A second question is if there are circumstances under which the opposition can be extended by a party to the proceedings, possibly up to the point where it becomes an unlimited opposition.
These two questions will be examined in part B of the present article. In this part A of the article, the order of the decision G 9/91 and the reasons carrying the decision will be scrutinized and the legal meaning of a limited opposition will be discussed in section II.

II. Limited Opposition

1. Nature of Opposition

The reasons of the decision G 9/91 stress that the opposition proceedings before the EPO have an effect coming close to national nullity proceedings, and that the opposition proceedings can “in principle” be considered as contentious proceedings between parties.[6] While the effects may be similar (e.g., revocation has an effect ex tunc, just as revocation/nullification in national proceedings), there are fundamental differences in the nature of these proceedings. The foremost such difference is the matter in dispute.

a) The matter in dispute
In nullity proceedings, the matter in dispute is the plaintiff’s claim or the relief sought. In contrast, the matter in dispute in opposition proceedings is the European patent, not the opposition.[7] The difference becomes apparent in the different orders of the decisions issued by the Opposition Division on the one side and the competent national courts on the other side. The order corresponds to what has been requested by one of the parties (at least in opposition proceedings where no minus may be awarded, but only that which is requested).

The set of possible orders is laid down in Art. 101 (2), (3) EPC, and corresponds to the set of possible requests.[8] Notably, the second sentence of Art. 101 (2) EPC, speaking of rejecting the opposition, deviates in terminology from the first sentence which speaks about an order to revoke the European patent, and also deviates in terminology from Art. 101 (3) EPC which speaks about an order to maintain the European patent (in amended form) or of a revocation of the European patent. Clearly, the matter in dispute can only either be the opposition or the European patent. The title of article 101, albeit not being legally binding, has the right of it by speaking only about revocation or maintenance of the European patent, i.e. about orders concerning the actual matter in dispute, the European patent. Art. 101 (2), second sentence EPC should read “Otherwise, it shall maintain the European patent”.[9]

A request of the opponent for revocation of the European patent in parts is not possible. To understand this better a model European patent shall be considered herein that has 4 claims, of which claims 1 and 3 are independent, and claim 2 depends on claim 1 and claim 4 depends on claim 3. Now, a request to revoke claim 1 is not possible because, unlike in nullity proceedings, such an order cannot be issued. It is likewise not possible for an opponent to reformulate this request positively by seeking maintenance of the patent in amended form, namely in the form of claims 2-4 (which would be renumbered as amended claims 1-3 according to EPO practice). The opponent cannot request maintenance of the European patent in a certain amended form either. It is established and undisputed that it is only the patentee who can amend the European patent to defend it (Art. 113 (2) EPC). The patentee and only the patentee can therefore request maintenance of the European patent in amended form. That means, the only valid request of an opponent is for revocation of the European patent.[10]

But if an opponent can only request revocation of the European patent, what then is the meaning of a limited opposition, i.e., an opposition in which the statement according to Rule 76 (2) (c) EPC indicates that the extent to which the European patent is opposed is not the patent as a whole, but, e.g., only claim 1?

b) Entire patent is always subject to opposition
Contrary to what is said in Reasons 10 of the decision G 9/91, a limited opposition does not mean that the subject-matters of claims 2-4 are not subject to opposition in the sense of Art. 101 EPC and that there are no proceedings in the sense of Art. 114 EPC in existence concerning such subject-matters,[11] and that the EPO has no competence to deal with them at all. If this were true, then claims 2-4 in the above example could not fall under any circumstances. However, if the patentee defends his patent only in the form as granted, and claim 1 is found not to comply with the EPC, then the entire patent must be revoked because the Opposition Division is bound to the patentee’s request and has no other choice.[12]

This finding by itself shows that the opposition always seizes the whole European patent, which is the matter in dispute as explained above. Further, even if the patentee requested maintenance of the opposed patent in amended form on the basis of some of the claims 2-4, e.g., on the basis of independent claim 3 and its dependent claim 4, then the Opposition Division would maintain the European patent as amended according to Art. 101 (3) EPC. Yet, in doing this, the Opposition Division explicitly does decide on claims to which the extent of the opposition according to Rule 76 (2) (c) EPC did not reach. Again, this result is the consequence of the Opposition Division deciding positively on the matter in dispute, the European patent, and not negatively in the sense of a ruling such as “Claim 1 is revoked”. The part of the order of the decision G 9/91 that says that the power of an Opposition Division to decide on the maintenance of the European patent depends upon the extent to which the patent is opposed is therefore misleading.

2. Legal Implications of the Statement of Extent

Although the wish of the opponent to limit the opposition expressed by the statement according to Rule 76 (2) (c) EPC does not constitute a (valid) request, it does have legal implications. In this respect, the decision G 9/91 frees the Opposition Division of the duty to examine a European patent amended in this way. But, what is more, G 9/91 does not only free the Opposition Division of its examination duty, but forbids any examination for compliance with the EPC in the case at hand. The question if the legal framework of the EPC allows a limitation of the duty and of the power of the Opposition Division to examine an amended European patent needs some attention.

a) The parties in interest
While the opponent and the patentee are parties to the proceedings, and the opponent typically has his own motives to oppose a European patent, there is also the public involved as a party of interest.[13] The interest of the public is to keep the register free of invalid patents.[14] The view that interests of the public play a role in opposition proceedings is further supported, e.g., by the possibility of the EPO to continue opposition proceedings even if the opposition was withdrawn (Rule 84 (2), second sentence EPC). This means that the opponent can initiate the opposition proceedings, but cannot terminate them, not even jointly with the consent of the patentee. That is why opposition proceedings are not fully governed by the principle of party disposition.[15] Opposition proceedings shall fairly balance not only the interests of the parties to the proceedings, but of the parties in interest, which includes the public.

b) Limitation of the duty to examine
While Art. 101 (3) (a) EPC requires an examination that the European patent in amended form meets the requirements of the EPC before a decision on the basis of Art. 101 (3) (a) EPC can be issued, the duty to examine is not unlimited. That is why Rule 76 (2) (c) EPC is not a rule which does not comply with the higher ranking articles (Art. 164 (2) EPC), but is a bound on the duty to examine cast into a legal norm. The reason that the Enlarged Board of Appeal was right to limit the duty of examination of the Opposition Division is – in last consequence – one of a balance of interests and procedural economy. The opponent lacks need of legal relief if the opponent amended the European patent as discussed. Now, it is only the interest of the public that has to be balanced against the interests of the patentee when the opponent is satisfied. In this case, the interests of the patentee will usually predominate given that the principle of procedural economy shall be respected. Hence, the opposition proceedings can and should be concluded without spending further resources of the EPO, unless there are exceptional situations where the interest of the public prevails. Situations where the interest of the public can prevail are indicated in the second part of the order of the decision G 9/91 (see 3. below).

c) Limitation of the power to examine
While the limitation of the duty of the Opposition Division is fully justifiable, the limitation of the power of the Opposition Division to examine needs further attention. Consider the case of withdrawal of the opposition. Withdrawal of the opposition shows that the opponent has no interest in the revocation of the patent (anymore). Still, the Opposition Division may continue opposition proceedings of its own motion (Rule 84 (2), second sentence EPC), balancing the interests of the public against that of the patentee. If the law allows an Opposition Division to continue opposition proceedings of its own motion even if there is no interest in revocation on the side of the opponent, the Opposition Division should also be able to continue opposition proceedings of its own motion if there is limited interest in the revocation on the side of the opponent.
The reason why the power to examine was limited in the decision G 9/91 was the wrong assumption that the EPO lacked the competence to examine because the parts of the European patent outside the extent to which the patent is opposed in the opponent’s statement are forever not part of the opposition proceedings and that the EPO lacks the power to decide thereon. As shown above, this assumption is not justified. The entire European patent is subject to opposition proceedings.

3. Examination of Subject Matter Outside the Statement of Extent as Laid Down by G 9/91

The order of the decision G 9/91 further says that subject-matters of claims depending on an independent claim which falls in opposition proceedings may be examined as to their patentability even if they have not been explicitly opposed, provided their validity is prima facie in doubt on the basis of already available information. Since – absent any need – dependent claims are never examined if the claim on which they depend falls in opposition proceedings, this order means the following. If the patentee requests maintenance of the European patent in amended form based on a granted claim that depended from an independent granted claim found invalid in opposition proceedings, then the Opposition Division can enter into substantive examination as to the patentability of such a claim provided its validity is prima facie in doubt on the basis of already available information, even if this claim has not been indicated to fall within the extent to which the European patent is opposed in the statement according to Rule 76 (2) (c) EPC.

a) No implicit coverage by the statement of extent
The reason for this order given in the decision G 9/91 is that such dependent subject-matters have to be considered as implicitly covered by the statement under Rule 76 (2) (c) EPC.[16] From the point of view taken by the Enlarged Board of Appeal that the EPO would lack the competence to deal with anything outside the extent indicated under Rule 76 (2) (c) EPC, this assumption of implicit coverage is the only way out if the desired order is the order reproduced above. However, this reasoning is not necessary because the opposition always seizes the whole patent, and the EPO has no issues with a lack of competence as discussed above. Moreover, this reasoning is also not convincing as it goes against all established ways how legal statements shall be interpreted. The indications made in the statement under Rule 76 (2) (c) EPC are precise, in particular since the EPO form forces the opponent to exactly indicate a list of claims if a limited opposition is desired. Such a precise statement does not allow a legal interpretation according to which something else was actually meant.

b) Principles of procedural fairness and procedural economy dictate the extent of examination
If a deviation from the extent indicated in Rule 76 (2) (c) EPC shall be made then, as mentioned above, this is justified if it fairly balances the interests of the parties, including the public. Given that the opponent is satisfied and only the interests of the public and of the patentee need to be balanced, then it is reasonable and fair to decree that the EPO shall have the opportunity to examine a European patent in amended form based on a formerly dependent claim if the validity of such a claim is prima facie doubtful based on information already available in the proceedings. Available information encompasses the information of the documents that were validly introduced into the proceedings and common general knowledge.

It is in the discretion of the Opposition Division whether substantive examination based on available information is carried out in this case. This follows from the wording of the order of the decision G 9/91 (“may be examined”). The case is comparable to the continuation of opposition proceedings by the EPO of its own motion (see Rule 84 (2) EPC speaking of “may be continued”). The exercise of this discretion, and the question if discretion was exercised properly, are analogous to the case of continuation of the opposition proceedings by the EPO of its own motion because the same balance between the public interest and the interest of the patentee has to be evaluated in both cases, while the opponent evidently has no more own interest. That means, the EPO shall examine a request to maintain the patent in amended form on the basis of claims not indicated in the statement according to Rule 76 (2) (c) EPC if the EPO would have continued the opposition proceedings of its own motion according to Rule 84 (2) EPC when faced with the same request.

4. Finality of the Statement of Extent

Further, the decision G 9/91 establishes that, once the opposition period is over, the limitation of the opposition – to be understood in the sense explained above – becomes generally final.[17] The opponent may generally not later make the opposition unlimited, e.g. due to a change of mind.

In this regard, a consideration discussed in the decision G 9/91 is that the function of the time limit set forth in Art. 99 (1) EPC, namely the double function of the opposition period within the legal framework of the EPC with respect to admissibility (Rule 77 (1) EPC) and establishment of the factual and legal framework for substantive examination,[18] would be pointless if a limited opposition could be extended after the opposition period.[19] These considerations are again carried by the false assumption that there are no opposition proceedings pending as far as claims outside the statement of extent are concerned.

a) Opposition period is not a limiting factor
The time limit of the opposition period is not the limiting factor and would not become pointless if the opposition could be extended. For instance, German law knows the extension of complaints, and the question if such extensions shall be allowed is answered with regard to fairly balancing the interests of the parties. In opposition proceedings, the question would also be under which circumstances one may consider such an extension to be justified. The answer is not derivable from the time limit of the opposition period and not from an alleged lack of competence of the EPO, but derives again from the principle of procedural fairness and from the principle of procedural economy.

b) Principles of procedural fairness and procedural economy are limiting factors
Regarding fairness, the Enlarged Board of Appeal notes that the patentee shall be given a fair chance to consider his position at an early stage of the proceedings.[20] This position is in line with the case law and the practice of the EPO that the parties’ cases shall be set out fully as early as possible, and anything late-filed, be it evidence or, as in this case, newly introduced means of prosecution or defence, are either not admitted or only admitted if certain conditions are met.
This goes hand in hand with considerations of procedural economy, which is the reason for the existence of a limited opposition. Continuing the example case from above, the European patent with the four claims, where the opponent filed a limited opposition indicating only claim 1 in the statement according to Rule 76 (2) (c) EPC, let us assume the opponent requested oral proceedings only for the case that claim 1 is defended by the patentee[21] and let us assume that the patentee requests maintenance of the European patent based on independent claim 3 and its dependent claim 4. Then the Opposition Division could issue a written decision at once, maintaining the patent in amended form according to Art. 101 (3) (a) EPC. This decision would not even have detailed reasons because the EPO is free of a substantive examination under these conditions. Evidently, such opposition proceedings could be over after a rather short amount of time.

c) Implications on the possibility to appeal
In this context, one may wonder if the opponent, whose only possibility is to request revocation of the patent, can appeal such a decision because he will formally not have obtained what he requested. Evidently, the answer should be no because the opponent declared in his notice of opposition that he does not have a legal interest in opposition beyond the indication made in his statement according to Rule 76 (2) (c) EPC. An appeal would be inadmissible due to lack of need of a relief. The statement about the extent to which the patent is opposed is therefore again not without legal consequences. It could be viewed as an implicit waiver of the right to appeal under the condition that the patentee will request, and the opposition division grant, maintenance of the European patent based on granted claims outside the indicated extent.[22] In fact, this case is special in that none of the parties can appeal because none of the parties is then adversely affected by the decision (Art. 107, first sentence EPC). This justifies why the decision, which does not have detailed reasons because no substantive examination was carried out, does not need to have detailed reasons.

5. Summary

To determine where the limits of the order of the decision G 9/91 lie, careful scrutiny of the reasons of the decision G 9/91 is necessary. The reasons appear to be partly based on incorrect assumptions about the nature of an opposition. Instead of a lack of competence of the EPO to examine and decide on subject matter outside the extent of opposition indicated in the statement under Rule 76 (2) (c) EPC, the principle of procedural fairness and the principle of procedural economy dictate how far the duty of an Opposition Division to examine reaches, and how far the power of an Opposition Division to examine shall go. Therein, the limit of the power is given by a dutiful exercise of discretion analogous to what is laid down in Rule 84 (2) EPC.
In consequence, a limited opposition can be extended in some cases after expiry of the opposition period if the extension respects the principles of procedural fairness and procedural economy. These questions will be dealt with in an additional part B of this article.

1. G 9/91, Reason 6 of the decision, presenting the position of the opponent.
2. Note that Art. 101 (1) in connection with Rule 81 (1) EPC only speaks of the examination of grounds of opposition invoked in the notice of opposition, but does not explicitly limit the examination to the extent to which the European patent was opposed.
3. For brevity, reference will only be made to the “Opposition Division” herein, but the same holds for a Board of Appeal.
4. G 9/91, Reason 6 of the decision.
5. G 9/91, Order.
6. G 9/91, Reason 2 of the decision.
7. If the matter in dispute were the opposition, then, for instance, continuation of the opposition proceedings by the EPO of its own motion (Art. 84 (2), second sentence EPC) would be impossible.
8. Besides procedural requests, such as a request to hold oral proceedings, which are of a different quality and cannot be put forth alone.
9. Notwithstanding, Rule 77 correctly speaks of rejecting the opposition because the inadmissibility concerns the opposition, not the European patent.
10. G 9/91, Reason 2 of the decision, says the opponent may seek a relief in the form of revocation of the patent as granted in parts. While the opponent may wish for an outcome of the opposition proceedings maintaining the patent in a certain amended form, this is not something that opponent can directly influence.
11. Following the reasoning of G 9/91 is the subsequent case law T 1066/92; T 443/93; T 31/08.
12. T 1019/92, reason 2.1 of the decision.
13. T 197/88
14. Schulte/Voit, Patentgesetz mit EPÜ,. 9. Auflage, § 81 PatG, mn. 39.
15. The principle of party disposition (in German: “Dispositionsmaxime”) concerns the question if the parties can fully dispose of the matter in dispute.
16. Likewise T 443/93.
17. The exceptions are discussed in section III. below.
18. G 9/91, Reason 6 of the decision.
19. G 9/91, Reason 10 of the decision.
20. G 9/91, Reason 6 of the decision.
21. This is a valid procedural request because the condition on which it depends is an inner-proc
22. The waiver is additionally subject to a reservation. The opponent reserves the right to extend the opposition if he is sued out of the opposed European patent (see section III.).