In Europe, in vivo diagnostic methods are excluded from patentability under Article 53(c) EPC due to socio-ethical and public health considerations. In decision G 1/04, the Enlarged Board of Appeal of the European Patent Office (EPO) noted in point 5 of the reasons that the phases to be caried out when making a diagnosis include:

1.  the examination phase involving the collection of data,
2. the comparison of these data with standard values,
3. the finding of a significant deviation, i.e. a symptom, during the comparison, and
4. the attribution of the deviation to a particular clinical picture, i.e. the deductive medical or veterinary decision phase.

According to said decision, a method claim comprising all said phases (i)-(iv) is to be considered as a diagnostic method not patentable under Article 53(c) EPC. In other words, it is possible to obtain protection for methods that do not comprise all said phases, e.g., methods comprising phases (i)-(iii) but without the final diagnosis phase (iv).

While decision G 1/04 implicitly advises omitting diagnosis phase (iv) from a method claim to leave the scope of exclusion from patentability under Article 53(c) EPC, there may be method claims that still require some claim features that are considered equivalent to said phase (iv). For example, it may be that a method claim was originally drafted for a jurisdiction that allows in-vivo diagnostic method claims, but that when said method claim comes to Europe, said problematic phase (iv) cannot be deleted from said method claim without contravening the support and disclosure requirements of Article 123(2) EPC, or said phase (iv) features are required for arguing novelty and inventive step in view of the prior art cited by the EPO.

Recent decision T 529/19, issued April 24, 2023, provides some applicant-friendly guidance on how to deal with such in vivo diagnostic method claims that still comprise wording that some EPO examiners consider to be covered by phase (iv). In said decision, the independent method claims started with the wording “A method for determining skin health …” or “A method for assessing the overall health of an individual …” prior to specifying phases (i)-(iii) as outlined in G1/04 cited above.

In said decision T 529/19, the Board of Appeal overruled the Examining Division’s finding that phase (iv) was derivable from said claim wording “for determining skin health” or “assessing the overall health of an individual” at the beginning of said method claims in question. In the Board’s opinion, said claims in question leave open what the determined “skin health” is or what “assessing the overall health of an individual” means, “… which, at most, represent an intermediate finding of diagnostic value”. (points 2.2 and 2.3 of the reasons). In this regard, it should be noted that the description mentioned “diabetes” as having an impact on the values in the data acquisition phases (i)-(iii) as a clear clinical picture in the sense of phase (iv), but, as the Board of Appeal noted in its decision, said clinical picture “diabetes” was not included into the method claims, which just referred to “skin health” and “overall health of an individual”.

Lesson learned from T 529/19: An in vivo diagnostic method can be claimed and is not excluded from patentability under Article 53(c) EPC if the attribution of the deviation derived from phases (i)-(iii) relates merely to “an intermediate finding of diagnostic value” (like “skin health” or “overall health of an individual”), i.e. not to a specific clinical picture (e.g. “diabetes”) to which the core of the invention is usually related. In other words, broadening the unallowed “clinical picture” to an allowed “intermediate finding of diagnostic value” paves the way to escape the in vivo diagnostic method exclusion provision of Article 53(c) EPC, as an alternative to the approach implicitly suggested in G 1/04 via omitting phase (iv), which is not likely to be a valid option in any case.