The European Patent Office’s (EPO’s) Enlarged Board of Appeal has recently handed down its decisions in cases G0001/05 and G0001/06, clarifying the law in relation to divisional filings at the EPO. They have predominantly confirmed that the legal position is that which existed before the Boards of Appeal at the EPO questioned the status quo, in that they have confirmed that divisional applications which contain matter beyond the scope of their parent applications can be amended to remove such matter, and that the subject matter which a divisional application is entitled to claim is determined not by the claims of the parent but by the scope of the totality of the parent application. However, they have recommended changes to the legislation which could significantly limit the ability to file divisional applications.

The Nature of Divisional Applications It is not uncommon for a patent application to contain multiple inventions. It may be because the inventor disclosed multiple ideas in the application, or because prior art discovered by the EPO during the application process has meant that a broad single invention ultimately becomes a number of more narrow inventions. However, the EPO will only allow a granted patent to claim one inventive concept. Consequently, when a patent application contains multiple inventions it becomes necessary to file divisional applications. Divisional applications are new applications which are based on the earlier application; the initial application being the parent, the divisional applications effectively being “its children”. A divisional application can only be filed whilst its parent application is still pending (i.e., yet to be granted). Divisional applications have the advantage that they are deemed to have the filing/priority date of their parent, but in return, they are not allowed to incorporate any subject matter not present in the parent application (there is no provision in Europe for “continuation-in-part”, as is available in the United States). If a divisional application does contain matter extending beyond that of its parent, it will be held to be invalid.

The First Set of Questions

It had been the practice of the EPO, where a divisional application did contain matter extending beyond that of its parent, to allow the applicant to amend the divisional application so as to delete this additional matter, thereby rendering the divisional application potentially valid. However, the Board of Appeal of the EPO, in case T39/03 (OJ EPO 2006,362), felt that this approach was wrong in law. Their interpretation of the relevant provisions (Article 76(1) EPC) instead led them to conclude that if a divisional application is filed with matter extending beyond that of its parent, the divisional application was not validly filed, and therefore should be deemed to have never been filed, and could not consequently be amended to correct this deficiency. Further, they felt that this was necessary in order to provide legal certainty for the public. In order to confirm this, the Board of Appeal referred three questions to the Enlarged Board of Appeal (the EPO’s highest authority), questioning whether a divisional application filed with matter beyond that of its parent can be amended in order to render it valid; if so, can this be done even when the parent application is no longer pending; and if the answer to both questions is yes, are there any further limitations imposed on such amendments.

The Second Set of Questions

These questions were augmented by referral from a second case (T1409/05), which raised further issues in relation to multiple generations of divisional applications. The EPO permits the filing of divisional applications based on other divisional applications, such that a chain of lineage is created, e.g. parent application, child (first divisional) application and grandchild (second divisional) applications (and in the case of T1409/05, great grandchild, third divisional, applications). In this case, the parent and child applications had been granted, with the grandchild application refused for containing subject matter beyond that of the parent and child applications. However, an issue arose because the subject matter of the great grandchild application, although containing subject matter extending beyond that of the initial application, did not contain any subject matter beyond that of the grandchild application. Consequently, the Board of Appeal referred the following question to the Enlarged Board of Appeal: in the case of a divisional application derived from one or more divisional applications, does the subject matter of the final divisional application have to be within the subject matter of all previous applications (both divisional and parent), or merely within the subject matter of the immediately preceding divisional application.

The Board of Appeal then went further, enquiring as to whether, in such a lineage of divisional applications, for a final divisional application to be valid, did each of the preceding applications have to be valid in terms of subject matter not extending beyond that of the immediate parent. The Board of Appeal also enquired as to whether the subject matter of the claims of a divisional needed to be nested within the subject matter of the claims of its divisional predecessors, i.e. was it a requirement that the claims of a subsequent divisional be no wider than the claims of its predecessor, regardless of the subject matter disclosed by any predecessor.

This last point was particularly controversial and it had the potential, if correct, to significantly limit the ability of applicants to carve out multiple inventions from their applications. However, the Board of Appeal felt that this was necessary to ensure legal certainty for third parties, as otherwise it would be possible for an applicant to keep one or more divisional applications pending for almost the entirety of the 20 year term of a patent, without third parties being certain that to exactly what subject matter the applicant was intending to claim.

However, others, including the president of the EPO, put forward the counterview that if this interpretation became law, applicants would simply file divisional applications claiming every embodiment disclosed in the parent application, so as to leave open the broadest possibility for filing future divisional applications, and this would in turn only increase the public’s legal uncertainty.

The Decision

In ruling on the above points, the Enlarged Board of Appeal reaffirmed the standard practices of the EPO, and rejected the more radical interpretations put forward by the Boards of Appeal. However, in the latter case, this was due more to what the position in law was, rather than what the Enlarged Board thought it should be.

The First Set of Questions

With regard to the first set of questions, the Enlarged Board ruled that if a divisional application was filed with subject matter extending beyond that of its parent, it was permissible to amend the divisional application so as to remove the offending subject matter in order to render the application valid. They drew support for this both from the European Patent Convention (EPC) itself, as well as the equivalent travaux prèparatoires (the papers detailing the discussions during the drafting of the EPC). Further, they felt that to hold otherwise would not significantly increase legal certainty for third parties, who would in any event be sufficiently protected by the fact that these applications could not be amended beyond the content of that which was initially disclosed. Instead, to not allow amendment would simply create a procedural trap which applicants would seek to avoid by filing divisional applications identical to their parents, which they would then amend at a later date. The only effect would therefore be the lengthening of the time taken to finalise divisional applications, increasing legal uncertainty for third parties.

In light of this, the Enlarged Board saw no reason to limit this ability to amend, to instances where the parent application was still pending, or otherwise.

The Second Set of Questions

Unsurprisingly, on considering the second set of questions, the Enlarged Board ruled that for a grandchild (or later) divisional application to be valid, its subject matter must not extend beyond that of the parent and each intermediate application. This was not a surprising decision, as the alternative would have left the way open for serious abuse of the patent system. Further, the Enlarged Board found no basis for disallowing a grandchild divisional application which complied with the requirements of the subject matter, simply because its parent application did not. Provided that the divisional application did not contain subject matter extending beyond that of all preceding applications, including the parent, it would be permissible, regardless of the status of any intervening applications.

Finally, the Enlarged Board confirmed that the claims of subsequent divisional applications need not be restricted to only that subject matter claimed in preceding divisional applications, and could instead claim any subject matter contained within the totality of the disclosure of each preceding application. This was based on the precise wording of Article 76(1) EPC, and given this wording the Enlarged Board felt they had no option but to rule otherwise. However, they expressed some regret at this, as they believed that it was undesirable that divisional applications could be used to maintain pending subject matter throughout the 20 year term of a patent without the public being given any certainty as to exactly what subject matter the applicant will ultimately claim. It suggested that those responsible for the legislation may wish to contemplate specific rules to limit this practice. However, such a change in legislation was beyond the scope of the powers of the Enlarged Board.

The Issues Arising Post-Grant

The Enlarged Board have thus confirmed that divisional applications can be amended during the application process to excise the additional subject matter, and that can also be done in relation to granted divisional applications under opposition before the EPO. However, this ability to amend is still subject to the usual conditions for amending a patent or patent application, which are considerably more restrictive after grant.

Other than under opposition at the EPO, there remains some uncertainty as to the ability to amend a divisional patent to excise subject matter after the grant of the patent, due to the vagaries of the different national laws of the member states. Post-grant amendment, other than in opposition, is currently the preserve of the national laws of the member states. Although the practices of the EPO are often persuasive, there is the potential for the various national jurisdictions to adopt an alternative approach to that of the EPO. Consequently, if a divisional patent is granted and subsequently found to contain added matter, then there remains the possibility that the patent will be found invalid by a national court in circumstances in which the proprietor is not permitted to make a rectifying amendment.

However, this should be mitigated, to an extent, by the coming into force later this year (most likely on 13 December 2007) of the EPC 2000, which replaces the current EPC. The EPC 2000 will give patent proprietors the right to amend their claims after grant via an ex parte application to the EPO (Articles 105a-c EPC 2000). As this is an EPO procedure, the principles of the EPO will apply, such that this should enable the proprietor of a divisional patent to amend the claims of the granted divisional patent in order to excise additional subject matter (although this right will still be subject to the usual restrictions on amendment). This will provide patent proprietors with an alternative mechanism for amending the claims of the granted patent, and may also influence the member states to adopt a more permissive regime for post grant amendment (as, for example, is expected to be the case in the UK).


The Enlarged Board has set out a reasonably liberal approach to divisional applications which should provide applicants with a sufficient degree of freedom to obtain patents on all the inventions contained in their applications. However, it will be interesting to see if the Enlarged Board’s comments regarding potential changes to the legislation are acted upon, in order to provide third parties with a greater degree of legal certainty within what the Enlarged Board defined as being “a reasonable time”. Changes to the EPC itself are notoriously difficult to achieve, as it requires a meeting of representatives of each member state (there currently being 32 members).

However, amendment of the full EPC is not necessarily required. Article 76(1) EPC specifically makes provision for the procedures for divisional applications to be governed by the Implementing Regulations of the EPC, which can be amended by the Administrative Council, a pre-existing body of the EPO which regularly makes decisions concerning patent law. Consequently, there is the potential for new restrictions on the scope of the claims of second and further generation divisional applications to be introduced into European patent legislation. Such legislation might echo the recently proposed changes to US patent law in which the applicant would be limited to filing only two continuation applications. However, it seems more likely that any change to European law would limit the scope rather than the number of divisional applications which may be filed.