Purity can be unconventional, a new position for the EPO boards of appeal (T 1085/13)

A recent decision by the EPO Technical Boards of Appeal (TBA) departed from previous boards on how the novelty of the increased purity of a known compound is to be assessed. In T 1085/13, the TBA diverged from previous decisions that established special criteria for determining the novelty of a claim directed to a known compound of increased purity. The decision also ignores the criteria set out in the EPO Guidelines for Examination.  These state that to be novel a selection invention must be “purposive”. The decision therefore confirms that the EPO is prepared to depart from its previous positions on the criteria for assessing the novelty of selection inventions. It seems that, for the purpose of assessing novelty, the TBA are now in favour of applying the same novelty criteria to these inventions as to any other type of invention, and nothing further.

The novelty of selection inventions

Increased purity is a type of selection invention. European patent law considers the selection from the prior art as novel under Article 54 EPC provided certain conditions defined by the case law are satisfied (EPO Guidelines for Examination, G-VI, 8.). Particularly, in order to be novel, the end points of a claimed sub-range or any point falling within the claimed sub-range must not be disclosed in the prior art. The end-points of the claimed range must also be "sufficiently removed" from the individual elements disclosed in the prior art.

The EPO Guidelines for Examination further state that a claimed selection must not be arbitrary. In other words, the claimed selection must constitute a "purposive selection" and be supported by some technical effect. The concept of purposive selection is explained in T 0198/84 (Thiochloroformates) (see r. 7) and T 0279/89 (r. 4.1).

However, the third criteria of purposive selection seems to have dropped from favour in recent years. In T 1233/05, the TBA observed that the requirement for a purposive selection of a claimed sub-range "appears to fall back upon considerations which should be taken into account in the assessment of inventive step rather than in that of novelty" (r. 4.4). The Board asserted that novelty should be assessed in view of the direct and unambiguous disclosure in a prior art document. This was also the view of the TBA in T 230/07 (Colloidal binder/PAROC) (Headnote and r. 4.1.6) (see also T 1130/09, r. 3.2 and T 1948/10, r. 3.6).

Notably, the UK Court of Appeal recently considered the issue of selection inventions, as defined in UK and European patent law, in Jushi v OCV (IPKat post here).

T 0990/96: Purity is conventional

Another historic departure from the "normal" requirements for the novelty of selection inventions has been the assessment of the novelty of increasing the purity of a compound. Following the 1998 decision in T 0990/96 (Erythro-compounds/NOVARTIS), purity has been considered a special case. Particularly, the burden of proof is placed on the applicant to show that the claimed level of purity was never achieved in the prior art.

T 0990/96 found that increasing the purity of an organic compound and the methods of doing so are conventional. As such, a document disclosing a low molecular chemical compound "makes normally available this compound to the public in the sense of Article 54 EPC in all desired grades of purity" (Headnote 1 and r. 7). The TBA nonetheless observed that exceptional situations may occur if it can be shown on the balance of probabilities "that all prior attempts to achieve a particular degree of purity by conventional purification processes had failed" (Headnote 2).

Many subsequent decisions have applied the reasoning of  T 0990/96 (see EPO Case Law of the Boards of Appeal, I-C-6.2.4). T 0219/98, for example, found that purity is not usually a distinguishing feature (Headnote, see also r. 4.8). T 0455/13 (Tolperisone/Sanochemia) confirmed that, purity does not confer novelty failing the exceptional circumstances defined in T 0990/96 (r. 3.9).

However, a decision of the TBA last year indicated that the special criteria for assessing the novelty of purity may be losing favour in a similar fashion to that of the “purposive selection” test.  In T 1085/13 the TBA found that the reasoning of T 0990/96 was contrary to the principles of novelty provided by the Enlarged Board of Appeal decision G 2/10 (Disclaimer/SCRIPPS), namely that novelty is destroyed only by a clear and unambiguous disclosure in the prior art.

T 1085/13: purity may not be conventional or implicit

T 1085/13 related to the novelty and inventive step of a claim directed to amorphous Lercanidipine Hydrochloride (LH) having a purity of at least 99.5%. During examination, the subject matter of the claim was found not to be novel because the applicant had not satisfied the requirements set out by T 0990/96 and shown that all prior attempts to reach the claimed level of purity had failed. The Examiner further found that the claim lacked inventive step.

The cited prior art mentioned amorphous LH in the form of hemihydrate LH, and included tables in which LH hemihydrate having an initial purity of 99.85% was indicated. A method for producing LH hemihydrate was disclosed in a further document referred to in the prior art. However, during appeal proceedings, the applicant filed a report claiming to show that the amorphous LH having a purity as high as 99.85% (or the claimed 99.5%) cannot be obtained by following the procedure indicated in the prior art.

The TBA was satisfied that the applicant's report demonstrated that the procedure described in the prior art would only achieve a LH purity of 97.91% as opposed to the 99.85% purity reported in the prior art. The TBA thus found that whilst the cited prior art appeared to anticipate the claimed subject matter (r. 2.2), anticipation requires that the prior art teaching must be reproducible by the skilled person (r. 2.3).

The TBA accepted that if the reasoning of T 0990/96 were to be followed, the novelty of the claimed subject matter would have to be denied in view of the prior art (r. 3.5). However, the TBA reasoned that such an outcome would not be in line with the case law of the Enlarged Board of Appeal (EBA) decisions on novelty G 2/88 (Friction reducing additive) and G 2/10 (Disclaimer/SCRIPPS).

Purity can be important

Particularly, the TBA observed that following the reasoning of G 2/10, "in order to conclude a lack of novelty, there must be at least an implicit disclosure in the state of the art of the subject-matter falling within the scope of the claim" (r. 3.6.1)". The concept of implicit disclosure is defined in T 1523/07: "[t]he implicit disclosure means no more than the clear and unambiguous consequence of what is explicitly mentioned".

Applying this reasoning, the TBA found that the claimed subject matter of the patent in question would not have been the clear and unambiguous consequence of the disclosure in the prior art. As such, "a claim defining a compound as having a certain purity therefore lacks novelty over a prior-art disclosure describing the same compound only if the prior art discloses the claimed purity at least implicitly, for example by way of a method for preparing said compound, the method inevitably resulting in the purity as claimed" (r. 3.7). If the method of the prior art has to be supplemented by additional methods, the skilled person would not inevitably have arrived at the claimed subject matter, and the claim is novel.

The TBA confined an assessment of whether the additional methods were common general knowledge to the assessment of inventive step, and as not relevant to novelty. Under this reasoning, the TBA found the claim to amorphous LH having a purity of at least 99.5% to be novel in view of the cited prior art. The TBA further found the claim inventive in view of the technical difficulties that would be faced by a skilled person in achieving the claimed purity in view of the prior art.

Final thoughts

As far as this Kat is aware, T 1085/13 is the first decision by the TBA to depart from the “special criteria” for purity inventions provided in T 0990/96 (although she is happy to be corrected on this if readers are aware of any earlier decisions).

T 1085/13 also appears to have ignored the criteria for selection inventions established by earlier TBA (and outlined in the EPO guidelines for examination) that a claimed selection must constitute a "purposive selection". This is in line with other recent decisions of the TBA. It therefore appears that the third criteria for the novelty of selection inventions is being phased out, although this is still not reflected in the most recent EPO Guidelines for Examination. If this really is to be the new position of the EPO, is it not time for these changes to be reflected in the guidelines? This Kat also awaits with interest to see whether this latest decision on purity inventions will be followed by subsequent boards and the Examiners.