Art. 52(4) EPC excludes inter alia diagnostic methods practiced on the human or animal body from patentability. For years there has been a discussion whether this provision only excludes a full and complete diagnostic method from patentability or whether preliminary steps (e. g. data acquisition via x-ray) practiced on the human or animal body are excluded from patentability already although the claim makes no direct reference to a diagnosis.

The President of the EPO referred this question to the Enlarged Board of Appeal back in 2003 and on December 16, 2005 the Board issued a decision holding that the diagnostic method patentability exclusion must be interpreted narrowly and only applies to claims directed to a full diagnostic method. (Decision G1/04)

Specifically, the Board held that for the patentability exclusion to apply a diagnostic method claim must comprise the following three elements:

a) the diagnosis to be made,

b) the preceedings steps of e. g. data acquisition which are constitutive for making the diagnosis, and

c) the specific interactions with the human or animal body which occur when carrying out the preceeding steps which are of technical nature.

This decision in principle opens the door to claims directed to data acquisition methods practised directly on the human or animal body. For example a claim merely comprising the step of x-raying the human body in a specific way without making a reference to the later diagnosis to be made should no longer be excluded from patentability under the new case law.

However, some caveats remain.

First, if the preceeding (data acquisition) step is invasive, the patentability exclusion of surgical methods will likely apply.

Second, the Board pointed to Art. 84 EPC (claim clarity) and held that any method claim must comprise all features which according to the disclosure of the application are essential for the invention. This seems to be an indication that it might not be possible to freely draft claims omitting the final diagnostic step so as to circumvent the patentability exclusion.

On the other hand the Board specifically says that intermediate findings of diagnostic relevance must not be confounded with a diagnosis for curative purposes strictu sensu (only the latter being excluded from patentability if practised on the human or animal body). This should clearly open the door to the patenting of non-invasive data acquisition methods which may later be used as a basis for a diagnosis.

The Board further clarifies that it is of no relevance for the diagnostic method patentability exclusion whether or not the presence of a medical practitioner is necessary when carrying out the method. A full diagnostic method practised on the human or animal body will therefore remain excluded from patentability even if it is possible to have e. g. laboratory personnel carrying out the method.

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