CASELAW-EPO - reviews of EPO Boards of Appeal decisions

T 1303/18 – On the validity of the priority – Reversal of the onus of proof

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The patent relates to a novel polymorphic form (form II) of Rotigotine, which form is useful for the manufacture of a stable medicament for treating or alleviating symptoms .of Parkinson ’s disease and other dopamine-related disorders.

Brief outline of the case

No less than 7 oppositions had been filed.

The patent was revoked and the proprietor appealed.

The validity of the priority was a crucial point in the discussion before the board.

Three priorities were claimed: D48=EP 07 121 795.4 and D49=US 60/990,721 both filed on the same day 28.11.2007 and EP 08166576 filed on 14.10.2008.

As the earlier priority was deemed not valid, a public prior use between the earlier and the subsequent priority was considered belonging to the prior art under Art 54(2) and proved fatal due to lack of N or IS for all requests on file.

The revocation was thus confirmed.

Non validity of the priority

As both earlier priorities were of the same date the board referred only to D49.

The opponents objected the validity of this earliest priority. They argued that the subject-matter of claim 1 as granted was not directly and unambiguously disclosed in D49. They referred to opinion G 2/98, OJ 2001, 413.

The question was thus whether the subject-matter of claim 1 as granted that is directly and unambiguously derivable from D49.

The proprietor’s point of view

The proprietor argued that there was no doubt that the claims as granted and the whole disclosure of D49 concerned the same invention within the meaning of Article 87(1) EPC and opinion G 2/98, namely, polymorphic form II of rotigotine.

The proprietor pointed out that the patent and D49 disclosed the same methods for characterising the mentioned polymorphic form and that the same figures resulted from this characterisation, thus demonstrating identity of the invention.

The proprietor further submitted that only form I and form II of rotigotine were known at the earliest priority date and form II was clearly distinguished from form I. Stating that the priority from D49 was not valid amounted to insinuating that a third polymorphic form of rotigotine existed but this was clearly wrong.

Additionally, the proprietor submitted that structural properties allegedly lacking in D49 were implicitly disclosed to the skilled person since they were inherent to polymorphic form II and accessible by using the disclosed analytical methods.

In this respect, the proprietor further submitted that in the appealed decision the OD inconsistently applied two different standards for the assessment of the validity of the earliest priority on the one hand and novelty on the other hand.

The board’s point of view

For the board, the fact that the same characterisation methods like X-ray diffraction, Raman spectrum and DSC calorimetry are used to describe the disclosed compound in both the patent and D49 plays no role when assessing the identity of invention under G 2/98.

Also the fact that the patent and D49 share the same figures is irrelevant; what is decisive is whether or not, using common general knowledge, a compound as defined in claim 1 of the patent is directly and unambiguously disclosed in D49 as a whole.

The board also recalled that the disclosure as the basis for the right to priority under Art 87(1) and as the basis for amendments in an application under Art 123(2) has to be interpreted in the same way and referred to G 1/03, OJ EPO 2004, 413, point 4 of the reasons and G 2/10, OJ EPO 2012, 376, point 4.3 of the reasons.

In claim 1 as granted, the claimed compound is said to be polymorphic form II of rotigotine and is defined by at least one of four properties, in particular property (a) a certain X-ray powder diffraction spectrum comprising four peaks with an error margin of ± 0.2, said to be measured with Cu-Kalpha irradiation (1.54060 Å).

Comparing the definition in terms of property (a) given in claim 1 as granted with the above disclosures in D49 reveals some differences.

For the board and in view of the established differences, it follows that, in order to arrive at the four peaks stated in claim 1 as granted, at least two selections within D49 are needed:

  • a first selection for defining the compound of D49 by means of a number of four peaks within the X-ray powder diffraction spectrum; and
  • a second selection for arriving at the specific diffraction angles (°2theta) mentioned in claim 1 as granted for these four peaks.

D49 did not contain any pointer towards these two specific selections.

The priority was thus not valid.

Additionally, claim 1 as granted defines the four mentioned peaks with an error margin of ±0.2. This margin has been broadened as compared with the error margin of ±0.1 disclosed in D49. This means that, according to claim 1 as granted, the peaks can be shifted so that they no longer match the diffraction angles (°2theta) disclosed in D49. No disclosure of this broadening of the error margin can be found in D49.

Therefore, the skilled person, at the relevant date of the subsequent filing, would not have derived a compound as defined by the X-ray powder diffraction spectrum mentioned in claim 1 as granted directly and unambiguously, using common general knowledge, from the disclosure in D49.

Similar conclusions were drawn for the three other properties.

For the board, it follows that the definition given for the compound referred to in granted claim 1 differs in numerous aspects from that disclosed in priority application D49. As a consequence, it cannot be concluded that the compound of granted claim 1 is the same as that disclosed in D49.

The board concurred with the opponents that by accepting the argument about the “theoretical” third form of rigotine, the earliest priority would become retroactively invalid if another crystal form of rotigotine was discovered later, which would fall under the definition given in claim 1 as granted but not under the disclosure of D49. Hence, this argument runs against the principle of legal certainty and must thus fail.

With respect to novelty, the mere reference to “polymorphic form II” of rotigotine in the prior art was sufficient to assume a novelty-destroying disclosure. On the other hand, the OD objected to a missing or slightly differing reproduction of the analytical data of granted claim 1 in D49 in a 1:1 manner and denied the disclosure in D49 of polymorphic form II of rotigotine as defined in granted claim 1 despite the fact that claim 1 as granted explicitly referred to “polymorphic form II” of rotigotine.

For the board, his argument is not convincing either. Priority has been claimed from a written disclosure (D49) and it is from this disclosure that the skilled person should have been able, at the relevant date, to derive directly and unambiguously, using common general knowledge, the subject-matter of claim 1 as granted. However, D49 does not disclose the same compound as that defined in claim 1 as granted.

Onus of proof

The proprietor also argued that the opponents bore the burden of proving that claim 1 as granted defined a compound different from the one disclosed in D49. No evidence in this respect had been presented.

The board held that it was the proprietor who introduced various differences between the compound defined in granted claim 1 and that disclosed in D49.

If, despite these differences, the proprietor asserts that the compound of granted claim 1 is the same as that disclosed in D49, it is the proprietor who bears the burden of proving this.

In fact, it is for an applicant to ensure, where priority from a previous application is claimed, that the same invention is defined, according to the required standard, in the subsequent application as filed.

Further aspects of the present case

The proprietor requested that specific questions be referred to the EBA. The proprietor argued that there was a risk of a contradiction between the case law on novelty and that on validity of priority and that the unitary concept of disclosure would be violated.

The board held that the request for a referral to the EBA rests on the precondition that the same polymorphic form is defined in both the claim at issue and the priority application. However, the board has concluded that the polymorphic form defined in claim 1 as granted is not directly and unambiguously disclosed in the priority application D49. The request for a referral was thus dismissed

The proprietor also argued that the subject-matter of the claims as granted was at least entitled to a partial priority from the earliest priority applications.  Since this argumentation was filed after filing the proprietor of the grounds of appeal, it was not admitted under Art 13(1) RPBA20 as the matter raised new complex issues at a late stage of the appeal proceedings.  


On the validity of the priority

The decision is interesting in that it puts the onus of proof of the validity of priority to the proprietor not only in formal but also in substantial matters.

In the same vein, but relating to formal aspects of priority, in T 1786/15 the board held that appropriate standard of proof to be applied in case or transfer of priority it is not the balance of probabilities, but like in cases where all evidence supporting a specific statement of fact (for instance a public prior use) is within the power and knowledge of one party, the boards apply a stricter standard of proof, namely the standard “beyond reasonable doubt“.

In T 1103/15, the board did not follow the argument that if there is uncertainty about the validity of the transfer of priority claim, the proprietor should enjoy the benefit of the doubt.

Last but not least, we should not forget that, as far as formal aspects of the transfer of priority is concerned, we have two pending referrals to the EBA, i.e. G 1/22 and G 2/22.

Reversal of the onus of proof

A reversal of the burden of proof against the applicant/proprietor is however not current in opposition or in examination. There are however some exceptions.

In the recent decision T 1009/20 (which I did not have time yet to comment), the board held that when using an unusual parameter the onus of proof lies with applicant when it comes to distinguish the subject-matter claimed from that of the prior art.

In T 2275/17, commented on LinkedIn, an unusual and obscure parameter, which can only be calculated was at stake, the onus of proof shifts and lies with the proprietor and not with the opponent under Art 123(3).

In T 1265/17, also commented on LinkedIn, the board held that, if a claim is unduly broadened with respect to the scope of the examples used to illustrate a technical effect, particularly when this broadening concerns the feature/s allegedly providing that effect, the burden of proof might shift back to the proprietor to prove that the effect observed in the examples would also be obtained throughout the entire scope of the claims.

In T 1388/10, the board held that if an applicant claims an exception under R 43(2), plurality of independent claims of the same category, he bears the burden of proof.

Benefit of the doubt

In T 658/90, the board held that in presence of contrary assertions of the parties in opposition about comparative examples, the benefit of doubt should be in favour of the party not having the burden of proof, i.e. in said case the proprietor.

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