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Issue 06/70 | December 11, 2006
Divisional Applications at the European Patent Office

1. Overview

1.1 The practice of filing divisional applications is familiar to many users of the system of law for the grant of patents enshrined in the European Patent Convention (EPC). A European divisional application can be filed relating to any pending earlier European patent application. This means that a divisional application can, in accordance with established practice, be filed at any time before the grant, rejection or withdrawal of an earlier European patent application.

1.2 The EPC implicitly provides for two ways in which a plurality of divisional applications can be filed. Firstly, once a divisional application is filed (a "first-generation" divisional), a further ("second-generation") divisional application can be filed taking as its immediate "parent" the first-generation divisional. The second-generation divisional can then act as a "parent" for another divisional, and so on. Thus, a sequence or cascade of divisional applications can be established. As long as a divisional in a sequence is pending, a subsequent divisional can be filed notwithstanding that chronologically earlier parents in the sequence may have matured to grant, been rejected or withdrawn. Secondly, more than one divisional application can be filed having the same immediate parent.

1.3 In theory, there is no limit to the number of divisional applications which can be filed in either way. However, in practice, the filing of divisional applications can be costly, not least because it may be necessary to pay, at the point of filing the divisional, all renewal fees which have been paid in respect of the immediate parent up to that point in time.

1.4 Provisions allowing divisional applications typically have the underlying purpose of allowing applicants an opportunity to pursue, in a divisional application, subject-matter which is seen as not corresponding to that of the parent (for example, subject matter relating to a different inventive concept, excised from the original claims of the parent as a result of a lack of unity objection). The national law of certain other European countries relating to divisional applications is more restrictive than the law as provided in the EPC. For example, under UK national law, it is necessary to bring a divisional application in order for grant within a time frame which is set by the parent case. However, under the EPC, a divisional application can be filed as late as the day before the grant of an earlier application, and, once filed, the divisional application is prosecuted independently of the parent. In some cases, this less restrictive structure at the EPO has led to the development of European practice which in some ways resembles the filing of US continuation applications.

1.5 Perhaps mindful of a growing trend in the reliance on the provisions for filing divisional applications, over recent months three distinct Technical Boards of Appeal at the EPO have referred a number of questions to the Enlarged Board of Appeal in order to clarify aspects of the law relating to divisional applications. The three separate referrals have now been consolidated and will be heard as one before the Enlarged Board. Naturally, these referrals have created an environment of legal uncertainty regarding divisional practice at the EPO and have immediate practical implications with respect to the filing and prosecution strategies which divisional applicants must currently consider.

1.6 The referrals are discussed separately and in turn below, and their implications for applicants are considered.

2. Validity of divisional applications

2.1 With a few minor exceptions, a statutory bar exists with regard to subject-matter which was added subsequent to the initial filing of a European patent application. Case law of the EPO Boards of Appeal has developed a particularly onerous test for added matter. A seminal case a number of years ago established that the burden of proof which applicants were expected to meet was synonymous with the standard for guilt in criminal proceedings - "beyond reasonable doubt".

2.2 Naturally, the issue of added matter must be considered in a divisional application with respect to an earlier application. However, the Guidelines for Examination at the EPO make it clear that applicants are afforded the opportunity of amending divisional applications in order to excise subject-matter added beyond the content of the earlier application, as filed. If such illegal subject-matter is not removed, then the application should be refused.

2.3 The key issue which vexed the Board in T0039/03, and which gave rise to the first referral, centred on the interpretation of Article 76(1) EPC. That Article, which provides for the possibility of filing divisional applications, reads as follows (our emphasis):

"A European divisional application ... may be filed only in respect of subject-matter which does not extend beyond the content of the earlier application as filed; in so far as this provision is complied with, the divisional application shall be deemed to have been filed on the date of filing of the earlier application and shall have the benefit of any right to priority."

2.4 With reference to the emphasised text, the Board considered that Article 76(1) should be interpreted such that a divisional application, which discloses subject-matter extending beyond the content of the earlier application as filed, is to be rejected effectively at the point of filing the divisional application. As such, a divisional application as filed which added subject-matter over the earlier application as originally filed would be incurably deficient — no subsequent amendment could remedy that initial defect.

2.5 To justify its position, the Board relied, inter alia, on the fact that the section of the UK Patents Act, which provides that amendments must not add subject-matter, was amended a number of years ago. This section previously contained language similar to that of Article 76(1). In an isolated case, the UK High Court, under the law prior to its amendment, held that a divisional application which added subject-matter over the parent was not allowed to proceed. Thus, the amendment to the UK Act was seen to correct the former provision which was considered to be unfair to applicants.

2.6 The Board in T0039/03 said (arguably incorrectly) that the former provision regarding divisional applications in the UK Act "obviously was intended to match the corresponding provisions of Article 76(1)". Thus, the Board implied that the meaning given to the UK provision prior to amendment was correspondingly the correct interpretation of Article 76(1).

2.7 The Board referred the following questions to the Enlarged Board of Appeal:

(1) Can a divisional application which does not meet the requirements of Article 76(1) EPC because, at its actual filing date, it extends beyond the content of the earlier application, be amended later in order to make it a valid divisional application?
(2) If the answer to question (1) is yes, is this still possible when the earlier application is no longer pending?

2.8 A third question was referred in this case. This question will be discussed in Section 3 below.

2.9 The interpretation of Article 76(1) applied by the Board in T0039/03 is clearly at odds with the established practice of the EPO in relation to the filing of divisional applications. There is no provision in the EPC that the mere presence of such subject-matter at the point of filing of the divisional renders the application incurably invalid.

2.10 However, and despite the clarity of the Guidelines, there have been several recent Technical Board of Appeal cases which have reached Decisions based on conflicting interpretations of Article 76(1). Some cases have applied an interpretation consistent with the Guidelines, whilst others have adopted similar reasoning to the Board in T0039/03.

2.11 The interpretation of Article 76(1) in the latter category of cases has focussed on the words "may be filed". Thus, for example, in the view of the Board in T0039/03, should the divisional application contain subject-matter extending beyond the contents of the earlier application as filed, the divisional was not validly filed. That is to say, the application was defective ab initio.

2.12 The Boards of Appeal in these cases appear to have overlooked the phrase in Article 76(1) "in so far as this provision is complied with, the divisional application shall be deemed to have been filed on the date of filing of the earlier application ...". This latter phrase provides tacit acceptance that two categories of subject-matter can exist in a divisional application at the point of its filing. One category includes subject-matter contained in the earlier application as filed, and which can be accorded the filing date of the earlier application. The second category includes subject-matter extending beyond the contents of the earlier application as filed, and which cannot therefore be accorded the filing date of the earlier application. Thus, it is argued, that the established practice of the EPO as set out in the Guidelines is consistent with the language of the Article considered as a whole.

2.13 Following T0039/03, the same issue arose in T1040/04 but in this case in relation to an appeal from a decision of the Opposition Division. The question referred essentially restated the question posed by T0039/03, albeit in relation to an opposition:

Can a patent which has been granted on a divisional application which did not meet the requirements of Article 76(1) EPC because at its actual date of filing it extended beyond the content of the earlier application, be amended during opposition proceedings in order to overcome the ground of opposition under Article 100(c) EPC and thereby fulfill said requirements?

2.14 This referral is arguably unnecessary, given the first question posed in the initial referral, since the correct interpretation of Article 76(1) must be absolute and must be retrospectively considered at the time of filing of the divisional application. It cannot depend upon whether the divisional, whose validity is under consideration, is a pending application or a granted patent.

2.15 Nevertheless, we await with interest the Decision of the Enlarged Board on these points. In particular, whether the less restrictive interpretation of Article 76(1), which underlies the established practice as set out in the Guidelines, and which is followed in the majority of cases by the Technical Boards of Appeal, will be validated.

3. Sequence of divisional applications

In the referring decision, T1409/05, two separate but related issues were raised in questions subsequently referred to the Enlarged Board in cases of divisional applications existing as part of a sequence or cascade. The referring Board termed these issues the "impeccable pedigree" and "nested claims" requirements.

3.1 The "impeccable pedigree" requirement

3.1.1 This issue can be seen as a logical extrapolation of the restrictive interpretation of Article 76(1) arrived at by the Board in, for example, T0039/03.

3.1.2 In T1409/05, the Examining Division had refused a third-generation divisional application in a linear cascade as being in contravention of Article 76(1). In refusing the application, the Examining Division had followed a previous Technical Board of Appeal Decision (T0555/00).

3.1.3 In that case the Board held, inter alia, that where, at the point of its filing, a divisional application contravened Article 76(1), because when filed it included subject-matter extending beyond the content of the earlier application as filed, then that divisional should not have been accorded a filing date. Thus, any subsequent divisional in a linear cascade must necessarily be refused as being invalid ab initio because the earlier application was never "validly filed". That is to say, the earlier application was never legally pending when the divisional application was filed.

3.1.4 The Examining Divisions in both T0555/00 and T1409/05 had applied the more restrictive interpretation of Article 76(1) by focussing on the phrase (our emphasis):

"A European divisional application ... may be filed only in respect of ...",

and apparently had not given due consideration to the phrase:

"in so far as this provision is complied with, the divisional application shall be deemed to have been filed on the date of filing of the earlier application ...".

However, it is argued that the latter clause implies that the validity of the subject-matter of the divisional application is assessed as part of a process, whilst the former clause, taken in isolation, suggests that the validity of the entire application is assessed at the point of filing.

3.1.5 Clearly disagreeing with the more restrictive interpretation of Article 76(1), the Board in T1409/05 alluded to the fact that there is no provision in the EPC or the implementing Rules which mandates that where added subject-matter is included in a divisional application, that divisional, and any subsequent sequential divisional, should not be accorded the filing date of the parent, and should thus be rejected effectively at the point of filing, simply because of the failure of certain subject-matter in one of the previous cases in the sequence to comply with Article 76(1) when filed. The Board concluded that the initial legal condition for according, to the divisional, the filing date of the parent is the pendency of the parent and not its compliance with the substantive requirement of Article 76(1) vis-à-vis added subject-matter. We await with interest to see if the Enlarged Board validates this interpretation.

3.2 The "nested claims" requirement

3.2.1 The second issue which has arisen in connection with sequences of divisional applications concerns whether the subject-matter which is allowed to be pursued in a divisional application must be derived from the claims of the earlier application, or whether such subject-matter can be derived from the specification as a whole.

3.2.2 The second-generation divisional, from which the application in suit in T1409/05 was divided, had two siblings. Both of those cases had been rejected and each decision was separately appealed. In both Technical Board of Appeal decisions, it was stated (emphasis added):

"For these reasons, it is the board's view that the invention or group of inventions defined in the claims of the parent application as divided out of the grandparent application determines the essential content of the parent application; and therefore to meet the requirements of Article 76 EPC any further divisional applications divided out of the parent application must be directed to objects encompassed by such invention or group of inventions."

3.2.3 Clearly, such a requirement goes well beyond the established practice of the EPO and, if validated, would impose significant restraints on applicants with regard to the subject-matter legally available for prosecution in a divisional application.

3.2.4 In the first referral on the validity of divisional applications, the Board, in T0039/03, had considered these two cases. Clarification of the "nested claims" requirement was therefore implicitly sought with reference to the last sentence of the third question referred in that case:

(3) If the answer to question (2) is yes, are there any further limitations of substance to this possibility beyond those imposed by Articles 76(1) and 123(2) EPC? Can the corrected divisional application in particular be directed to aspects of the earlier application not encompassed by those to which the divisional as filed had been directed?

3.2.5 Despite the existence of this third question, the Board in T1409/05 sought to explicitly clarify this interpretation of Article 76(1) by referring the following questions (Board’s emphasis):

(1) In the case of a sequence of applications consisting of a root (originating) application followed by divisional applications, each divided from its predecessor, is it a necessary and sufficient condition for a divisional application of that sequence to comply with Article 76(1) EPC, second sentence, that anything disclosed in that divisional application be directly, unambiguously and separately derivable from what is disclosed in each of the preceding applications as filed?
(2) If the above condition is not sufficient, does said sentence impose the additional requirement
(a) that the subject-matter of the claims of said divisional be nested within the subject-matter of the claims of its divisional predecessors?
or
(b) that all the divisional predecessors of said divisional comply with Article 76(1) EPC?

3.2.6 Interestingly, the Boards, in T0720/00 and T0797/02, had applied a narrower construction to Article 76(1) because, in its view, if the subject-matter of a subsequent divisional was not derived from the claimed subject-matter of the immediate parent, then third parties would be left completely uncertain during most of the life of a patent as to how much of the subject matter of the earlier application might still be claimed.

3.2.7 The referring Board in T1409/05 doubted both whether it would be legally proper to arrive at such a construction of Article 76(1) and whether the concerns which were advanced to justify such a construction were any different for divisional applications in comparison with non-divisional applications. The Board noted that the underlying principle of divisional applications was to allow applicants the benefit of pursuing subject-matter in a separate application where a decision of non-unity had been reached vis-à-vis the earlier application. As such, Article 76(1) should not be interpreted so as to prevent applicants from benefiting from this possibility in subsequent divisional applications. In its view, such a construction would be tantamount to legislative activity reserved only for the Administrative Council or a diplomatic conference of the Contracting States.

4. Implications for applicants

4.1 Whilst these aspects of the law remain to be clarified, applicants considering filing divisional applications should, wherever practically possible, consider filing a divisional from an earlier application which is the original European patent application as initially filed, and, file as a divisional application, a carbon copy of the earlier application as filed. Only this way will applicants safely avoid any objections of added subject-matter and any discrepancies between subject-matter claimed in both the divisional and the earlier application.

4.2 This course of action, however, may not appeal to a certain category of applicants, for example, those who are filing divisional applications in order to pursue subject-matter which has not previously been searched in the parent case (the Enlarged Board of Appeal held some time ago that unsearched subject-matter cannot be subject to substantive examination). This could occur, for example, where there was a previous objection of lack of unity, or where there was an incomplete search, perhaps on account of claims being unclear and thus unsearchable. Since amendment of the claims is not possible before the issuance of the European Search Report, the filing as a divisional of a carbon copy of the parent (i.e. with the same claims) will simply lead to a repeat of the initial objection. In the former case, a supplementary search based on amended claims might provide a route to the pursuance of previously unsearched subject-matter. In the latter case, the scope of the initial search could be informally protested by filing arguments in support of the allowance of a broader supplementary search.

4.3 Considerable support exists in favour of the established practice of the EPO in relation to divisional applications, from both applicants and practitioners alike. Significantly, in response to an invitation to comment on the issues raised in the current referrals, Professor Alain Pompidou, President of the EPO, has recently made his views known. In his opinion, a divisional application not meeting the requirements of Article 76(1) in its version as originally filed should be treated as a European patent application, and should be allowed to be amended at any later stage in examination, regardless of the status of the earlier application. Furthermore, in his view, a divisional application should be allowed to be directed to aspects of the earlier application not encompassed by those to which the parent and subsequent predecessors in a sequence were directed. Professor Pompidou commented:

"The categorical view taken in recent decisions that divisional applications offending against the provisions of Article 76(1) EPC are invalid divisional applications is, in my opinion, unjustified."
4.4 Nevertheless, should the Enlarged Board of Appeal choose to validate the restrictive interpretations given by certain Technical Boards of Appeal, both existing and future divisional applicants may face significant prosecution problems. Not least, it will be of paramount importance to carefully draft the claims so as to preserve the legality of the application but at the same time retain the maximum scope of protection required by the applicant.

To discuss this topic further, please feel free to contact Marc Wilkinson (marc.wilkinson@hlbbshaw.com), at HLBBshaw, in Essex, UK.

The information contained in this email is provided for informational purposes only and does not represent legal advice. Neither the APLF nor the author intends to create an attorney client relationship by providing this information to you through this message.

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