All change for priority at the EPO? A referral is reviewed

EPO: some important issues have been flagged
for close attention and an authoritative ruling

The European patent fraternity has been buzzing with excitement over the referral of some of its most controversial issues involving the priority of patent claims to an Enlarged Board of Appeal of the European Patent Office for what, it is hoped, will be some definitive answers. If nothing else, this referral is likely to press the pause button on a substantial number of ongoing proceedings, as interested parties apply for a stay until such time as the Enlarged Board delivers its ruling.  This clear, helpful guest post from Carpmael & Ransford's David Holland, explains why these questions are being asked, so readers can appreciate what their real-world significance might be.

All change for priority at the EPO? 

A new referral to the EPO’s Enlarged Board means that there could be a new test for partial priority at the EPO. At the very least, the referral invites the Enlarged Board to provide clarification of the current test set out in an earlier Enlarged Board decision G 2/98. The UK Courts regularly refer to G 2/98 when assessing priority, as seen in Nestec v Dualit in which Arnold J refused a request for partial priority on the basis of the test set down in G 2/98.  It therefore seems likely that any changes instituted by the Enlarged Board will be felt not just at the EPO but in the national courts too. 

Partial priority: what is it and what does it do? 

Partial priority allows part of a claim which is contained in a patent application to be entitled to an earlier date, where some but not all of the alternatives covered by the claims appear in the priority document (a provisional filing), a concept permitted by Article 88(2) of the European Patent Convention (EPC). The current test for applying Article 88(2) EPC was set down by the Enlarged Board in G 2/98 and permits partial priority provided “it gives rise to the claiming of a limited number of clearly defined alternatives” (Reasons 6.7).

Eugene Markush

For example, a claim to “compounds A or B” where only compound A appeared in the priority document would be entitled to the earlier date, but in relation to compound A only. The “A or B” scenario is simple and uncontested. The divergence between the EPO decisions that led to this referral occurs where a claim generically covers compound A, e.g. by using a generic term or Markush grouping, but does not “clearly define” compound A as an alternative in the text of the claim. Certain EPO decisions (such as T 1222/11 and T 571/10) are generous and assign partial priority by “conceptually” dividing the claim into the “limited number of clearly defined alternatives” required by G 2/98.  The conflicting strict decisions (such as T 1877/08 and T 476/09) argue that mere “conceptual” division of a claim is not permitted by G 2/98, and that instead the text of the claim must identify those alternatives in order for partial priority to be acknowledged. 

The strict test can seemingly never be satisfied by ranges or other generic terms in a claim, as the text of such terms cannot be divided into a limited number of alternatives, whereas the generous approach may allow these generic terms to be divided up and so awarded partial priority.  For example, a range of “5 to 6” in a priority document that had been broadened to a range of “5 to 7” in the claims of the application would completely lose priority under the strict approach, but have partial priority in the range “5 to 6” under the generous approach. Clearly, these two different approaches have serious implications for patent validity where there is intervening art.

The first four questions: how to assess partial priority? 

The questions referred to the Enlarged Board not only ask the Board to decide between these strict and generous approaches, but also give the Board the option of totally abandoning the G 2/98 test  for partial priority, replacing it with a new test, or providing clarification as to how the test should be applied.

Question 1 asks if it is ever possible to deny priority for subject-matter first correctly disclosed in the priority document, where that subject-matter falls within a generic claim: 

“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?”

Question 1 therefore invites the Enlarged Board to remove G 2/98’s “limited number of clearly defined alternatives” test altogether, at least for “generic” claims.  It is unusual for the Enlarged Board to overrule its previous decisions, but this is by no means impossible (e.g. G 1/84 was overruled by G 9/93).

If the Enlarged Board answers “no” to question 1, it would accept that subject-matter first disclosed and enabled in the priority document and encompassed by the claim is entitled to priority regardless of any other considerations. This outcome would end the referral, as the other questions are conditional on an answer of “yes” to question 1. 

Nestec: not just a storm
in a coffee-cup ...

An answer of “no” to question 1 would contrast with the UK Court’s approach in Nestec v Dualit, where Arnold J held that three different housing arrangements covered by the claim were not clearly defined alternatives and so did not qualify for partial priority [2013] EWHC 923 (Pat), paragraph 96.  As a result, Arnold J held that the patent lacked novelty over the publication of the priority document under the UK’s equivalent to Article 54(3) EPC (section 2(3) UK Patents Act), a so-called “poisonous priority” attack. 

If the Enlarged Board considers that the mere disclosure of subject-matter in the priority document (as described in question 1) is not enough to permit partial priority for that part of a generic claim, it has to answer yes to question 1 and so move on to question 2:

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?

Question 2 therefore asks whether the “limited number of clearly defined alternatives” test from G 2/98 is the correct test to use for generic claims.  If the G 2/98 test is found to be the correct one, then the Enlarged Board will move on to question 3, which asks how to use this test: 

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?

If the Enlarged Board disagrees with the G 2/98 test, it does not need to consider question 3 but is instead asked to set a new test in question 4:

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

Accordingly, in answering these four questions the Enlarged Board should either remove or clarify the existing partial priority test from G 2/98. A review of the decision referring these questions suggests that the referring Board may have formed a view regarding the correct answer to at least the first four questions. 

The questions referred are accompanied by around 60 pages of legal background produced by the referring Board, including a comprehensive review of the EPO’s case law and how this has been interpreted by the UK Courts (including Nestec v Dualit).  The referring Board concludes that, before G 2/98, a more generous approach was accepted.  The Board finds no mention of the G 2/98 test in these earlier decisions and states that they were not explicitly overruled in G 2/98. The Board also notes that one of the reasons underlying the decision in G 2/98 (evidence of the legislative intent from a contemporaneous FICPI Memorandum) may seem to support a more generous approach to partial priority.

These observations, coupled with the sweeping nature of question 1 as asked by the referring Board, perhaps suggest that this referring Board favours total abandonment of the G 2/98 test for partial priority. The Enlarged Board will make its own decision, and it is likely that it will be assisted by a significant number of amicus briefs from interested parties.

The fifth question: toxic divisionals 

The referring Board was faced with the “toxic divisional” attack, as discussed at length on Tufty the Cat’s blog here, an attack closely related to the “poisonous priority” attack in Nestec v Dualit. The fifth and final question ensures that the Enlarged Board must address this attack even if it requires a strict test for partial priority:

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?”

Grandpa: one family member
who retained his priority date

In the “toxic divisional” attack, the strict G 2/98 approach to partial priority is applied by an opponent in order to invalidate a priority claim. The opponent then argues that a family member (a parent or divisional of the patent in suit) is novelty destroying under the EPO’s novelty-only prior art provisions (Article 54(3) EPC).  This attack relies on a more specific disclosure in the priority document (often an example) which is entitled to priority, set against a generic claim which is not entitled to priority (often because the claims were broadened when filing the application claiming priority).  As a result, the patent loses priority for the broadened claims, but the more specific disclosure in the family member retains its earlier date and so is citable as novelty-only prior art.  

Nestec v Dualit was not a toxic divisional attack because the novelty citation was the priority document (which had, unusually, been allowed to publish as a conventional patent application), rather than a parent or divisional.  While the toxic divisional attack has yet to be the subject of a UK Court decision, it was apparently accepted by an EPO Technical Board of Appeal in T 1496/11, although the issue is hardly discussed in the written decision leading many to question whether it is good law. 

If the Enlarged Board considers that the disclosure of subject-matter in the priority document (as described in question 1) is enough to permit partial priority for that part of a generic claim, then this would provide a permanent antidote to the “toxic divisional” problem.  If the Enlarged Board takes this route (by answering “no” to question 1) then all toxic divisional attacks must fail, because the generic claim would be always entitled to partial priority for any disclosure that appeared in the priority document.  As a result, no family member (parent or divisional) could contain a novelty-destroying disclosure with an earlier effective date.  This would be a simple solution to years of argument on this “toxic divisional” topic, but could potentially cause other complications.

The referring Board clearly appreciates the importance of comprehensively addressing the “toxic divisional” problem, because if the Enlarged Board either confirms and clarifies the G 2/98 test (question 3), or creates a new test (question 4), it must then answer question 5.  Question 5 asks whether a family member (parent or divisional) can ever be novelty-only prior art, regardless of partial priority.  There are a number of underlying legal and public policy points that have been used by patentees to argue that family members are never citeable for novelty against each other. It will therefore be fascinating to see how the Enlarged Board chooses to clarify the law in this area, if such clarification is still required following the answer to question 1.

Time for clarity -- and for dispelling spectres?

The answers to the referred questions will rewrite, or at least clarify, the concept of partial priority. It seems likely that patentees with ongoing actions in which partial priority is pleaded may request a stay until the referred questions have been answered.  If allowed, any stay would last for at least a year, as it is unlikely that the Enlarged Board will issue a decision for quite some time.   

No matter how the Enlarged Board answers the first four questions, it will have to address the “toxic divisional” problem head on.  In light of the increasing number of “toxic divisional” attacks following their apparent validation in T 1496/11, many will hope that the Enlarged Board both clarifies the law regarding partial priority and conclusively dispels the spectre of “toxic divisionals”.

This article is based on a client practice note available from Carpmaels & Ransford’s website here and first publicised on twitter by @CRPharmaIP.