Swiss cheese, calcium salt, partial priority and poisonous divisionals: an exotic feast for patent enthusiasts

It is a pleasure when this weblog can report on something to do with European patents that has nothing to do with power politics and everything to do with what the patent system is all about: operating a system of rules that is designed to separate the novel wheat from the previously-disclosed chaff in order to ensure as far as possible that only patentable inventions receive patents. Sometimes this happens at a positively nerdish level of detail.  This guest blogpost from Susan Keston (Patent Director, HGF Ltd) illustrates a level of legal sophistication in the applicability of patent law to the facts of individual applications that lies way beyond the imagination of the casual reader of the European Patent Convention.  This is what Susan writes:
Decision T0571/10 (decision date 3 June 2014 but online only on 27 November) makes an interesting contribution to the debate on partial priority. This decision affirms decision T1222/11 by departing from the strict and literal interpretation of the words “provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters” adopted in a number of previous decisions (T1877/08, T476/09, T1443/05 and T1127/00). This limited number of clearly defined alternatives condition was first introduced by G2/98.

"I have Swiss Cheese", by Nicole Wong*
The decision T 0571/10, referred to the FICPI memorandum (Example 1) to justify its rationale of using a “swiss cheese” approach to partial priority. In particular, for a term in the claim that is generalised relative to the disclosure of the priority document, the generalised claim is priority-entitled for the subset of the claim scope that is clearly and unambiguously disclosed by the priority document and everything outside that subset but within the scope of the generalised claim is not priority-entitled.

The priority document of the patent in suit (application number 08165575.5) for T 0571/10 disclosed (i) a particular calcium salt as an active agent; and (ii) a tribasic phosphate salt in which the cation is multivalent. The particular calcium salt was generalised to a generic class including the calcium salt “or a pharmaceutically acceptable salt thereof” and the tribasic phosphate salt was generalised to an “inorganic salt”. The Board held that it was not necessary that the clearly defined alternative subject matters were spelled out as such in the application (paragraph 4.5.12 of decision). The Board carved out the generalised claim filed during oral proceedings into two clearly-defined alternative subject-matters as follows:
Priority entitled: pharmaceutical composition comprising the calcium salt of the generic class (dihydroxyhept-6-enoic acid) as the active ingredient and tribasic phosphate salt in which the cation is multivalent.

Not entitled to priority: pharmaceutical composition comprising the generic class of acid or a pharmaceutically acceptable salt thereof as the active ingredient and an inorganic salt in which the cationic multivalent, wherein the active ingredient is other than the calcium salt of the acid and the inorganic salt is other than the tribasic phosphate salt in combination.
Decisions T 0571/10 and T1222/11 were both associated with Board 3.3.07. This new decision is relevant to the contentious issues of toxic priority and poisonous divisionals, which arise due to the strict literal interpretation of the “limited number of clearly defined alternative subject-matters” rejected in T0571/10.
* This lovely painting is available to purchase by auction. Merpel hopes that one of our readers will buy it ...
Swiss cheese, calcium salt, partial priority and poisonous divisionals: an exotic feast for patent enthusiasts Swiss cheese, calcium salt, partial priority and poisonous divisionals: an exotic feast for patent enthusiasts Reviewed by Jeremy on Friday, December 05, 2014 Rating: 5


  1. An approach which would remove the danger of poisonous priorities/divisionals, but has not made it to the guidelines yet (F-VI, 2.2). A bit of legal uncertainty in the meantime, luckily affecting only priority-claiming applicants...

  2. A very elegant solution, which the IP Kat itself already had anticipated and designated 'Tufty's law'. The concept that has been laid down by the Board may be applicable in 54(3) cases, but it will still have to be seen if amending the claims in such a way would be deemed allowable under Art. 123(2) in other cases.

  3. Bart makes a good point about whether or not carving up the generic claim into: (i) a priority entitled portion; and (ii) the generic claim with a disclaimer to the priority-entitled portion, may add subject-matter.
    The conditions for an allowable disclaimer G1/03 and G2/10 would have to be satisfied. For EPC Art 54(3) prior art the disclaimer is allowable only for re-establishing novelty. This would seem to be automatically satisfied in the case of the Art 54(3) document being the applicant's own priority document.
    I wonder if this is a European-specific problem with partial priority? In the US there is no counterpart of the novelty-only citation and USC 35 102(a) (2) together with 102(b)(1) seem to prevent self-anticipation.
    However, in the US can problems arise with carving up a claim that is broadened relative to the priority document if third party prior art is at issue? Does US law allow the generic claim to be carved out in accordance with Tufty's law to re-establish novelty over the third party prior art?

  4. When Board 3.3.07 splits the claim into a portion which is entitled to priority and a portion which is not, it is a purely conceptual analysis. It doesn't involve an actual amendment to the claim. I therefore don't think Article 123(2) is an issue.

    Likewise, there is no disclaimer in the claim, so it is not necessary to worry about whether one would be allowable. In fact, the applicant in T 0571/10 offered a disclaimer, but the Board felt it was not necessary.

    There might be an argument about whether a split which is merely conceptual meets the G2/98 requirement that the alternatives be "clearly defined". T 0571/10 says that it does, and that it is not necessary for the alternatives to be spelt out in the application itself (point 4.5.12 of the Reasons).


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