According to the EPO Guidelines for Examination, a claim defining a compound as having a certain degree of purity in principle lacks novelty over a prior art disclosure describing the same compound even if said prior art does not explicitly or implicitly disclose said claimed purity. See item G-VI, 7. “Examination of novelty” of the EPO Guidelines, as cited below:

A known compound is not rendered novel merely because it is available with a different degree of purity if the purity can be achieved by conventional means (see T 360/07).

However, said principle, i.e., combining the prior art disclosure with knowledge of conventional means in a supplementary manner for arguing lack of novelty, is no longer valid in view of decision T 1085/13 of November 9, 2018. T 1085/13 states that novelty  has to be assumed if the prior art disclosure needs to be supplemented, e.g., by a suitable (further) purification methods allowing to arrive at the claimed purity. Rather, this would be a matter to be considered in the assessment of inventive step.

Although this new approach in assessing novelty of degree of purity inventions according to decision T 1085/13 is of considerable practical importance, which is also reflected in the EPO’s internal distribution code “B” (To Chairmen and Members) on the cover page of said decision, the annually updated EPO Guidelines unfortunately still (four years after T 1085/13) show the above cited outdated and applicant-unfriendly examination approach. This can have a significant impact on the patentability of an invention, e.g., for inventions which must just get the hurdle of novelty in view of prior art which is not citable under inventive step [so-called Article 54(3) EPC prior art].

Applicants struggling with EPO examiners still applying the outdated novelty approach according to the EPO Guidelines are advised to rely on the decision T 1085/13 and the subsequent recent decision T 43/18 of June 1, 2022 in their favor to circumvent the novelty hurdle. This makes sense in particular because neither of the two decisions has been published in the EPO’s Official Journal and may even be unknown to EPO examiners just looking up the above cited (and insofar outdated) Guidelines for Examination.