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Partial Priority and ‘Toxic Divisionals’ at the EPO

Partial Priority and ‘Toxic Divisionals’ at the EPO

21/12/15

A number of questions relating to partial priority and its implications to so-called toxic divisional applications have recently been referred to the Enlarged Board of Appeal of the European Patent Office as case G1/15.

The term ‘partial priority’ relates to the situation where only a portion of the claim is entitled to a priority date - for example where a claim covers two or more alternatives.  Consider, for example, a situation where a claim covers A or B and the application claims priority from two earlier cases, the first of which discloses A, and the second of which discloses B.  In this example, the part of the claim relating to A can benefit from a priority claim to the first case, and the part of the claim relating to B can benefit from a priority claim to the second case. 

However, if the claim relates to a combination of features, for example, A and B, it cannot claim priority from documents which disclose either only A or only B, or from a single document disclosing A and B as alternatives.  An application with a claim to the combination of A and B would only be entitled to claim priority from an earlier application which disclosed the combination of A and B. 

Whilst this is a straightforward concept, there has been some uncertainty about its application following the decision of the Enlarged Board of Appeal in G2/98.  In G2/98, the Board decided that the use of a generic term or formula in a claim for which multiple priorities are claimed is allowable “provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters”.  However, unfortunately, it has not been clear how the phrase “a limited number of clearly defined alternative subject-matters” should be interpreted.

One way in which this has been interpreted is that where the office or a court finds that there is not a limited number of clearly defined alternative subject-matters, a claim to partial priority might well be invalid.  This can give rise to so-called toxic divisional applications where a priority claim of a divisional application is found to be invalid, such that the parent application, which does have a valid priority claim, can be cited as novelty-only prior art against the divisional application.  A similar situation can occur where the priority claim of the parent is invalid and that of the divisional is valid.  In this case, the divisional will be citable for novelty against the parent.

Many commentators have suggested that this potential for self-collision is an unintended consequence of the decision and its result is absurd.

In view of the uncertainties, the following questions have been referred to the Enlarged Board of Appeal:

1. Where a claim of a European patent application or patent encompasses alternative subject-matters by virtue of one or more generic expressions or otherwise (generic "OR"-claim), may entitlement to partial priority be refused under the EPC for that claim in respect of alternative subject-matter disclosed (in an enabling manner) for the first time, directly, or at least implicitly, and unambiguously, in the priority document?

2. If the answer is yes, subject to certain conditions, is the proviso "provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters" in point 6.7 of G 2/98 to be taken as the legal test for assessing entitlement to partial priority for a generic "OR"-claim?

3. If the answer to question 2 is yes, how are the criteria "limited number" and "clearly defined alternative subject- matters" to be interpreted and applied?

4. If the answer to question 2 is no, how is entitlement to partial priority to be assessed for a generic "OR"-claim?

5. If an affirmative answer is given to question 1, may subject-matter disclosed in a parent or divisional application of a European patent application be cited as state of the art under Article 54(3) EPC against subject-matter disclosed in the priority document and encompassed as an alternative in a generic "OR"-claim of the said European patent application or of the patent granted thereon?

As the Board’s decision on these questions may impact on other pending cases, the President of the EPO has allowed proceedings before the Examining and Opposition Divisions of the EPO to be stayed where their outcome depends entirely on the decision of the Enlarged Board of Appeal.  The cases affected will be those claiming subject matter for which the validity of the priority claim impacts on the assessment of novelty and/or an inventive step, where the claim in question uses one or more generic expressions, such as a chemical formula, a continuous range of numerical values or a functional definition and where the claim in question relates to subject matter which is more general than the subject matter disclosed in the priority document.

The EPO will notify parties involved in cases that are to be stayed and will withdraw any communications which set a deadline.  Parties will be notified once the proceedings are to be resumed following issuance of the decision of the Enlarged Board of Appeal.

In recent weeks, a number of amicus curiae briefs have been filed in connection with the referral.  The briefs provide an opportunity for individuals or groups who are not party to the proceedings and who are independent from those who are party to proceedings but who have a particular interest in the outcome of the decision to provide submissions to try and influence the Board’s decision.  The briefs submitted to date can be found at: https://register.epo.org/application?number=EP98203458&lng=en&tab=doclist.  The general consensus is that partial priority should not be refused for generic “OR” claims since the allowance of partial priority is in-keeping with the fundamental principles behind the laws governing priority. 

Further developments in the referral will be reported in due course.