8. Die Fachperson

In T 1632/22, In ex parte case T 1632/22, the application related to liveness detection in relation to authentication, e.g. when unlocking a phone based on a face image. The application proposed to categorise the images as a function of their "quality" and to use different liveness detectors for each quality type. The examining division concluded there was a lack of inventive step over D1 (face authentication).

With an amendment in substance to define the quality parameter used to define the quality type, the new feature of claim 1 was not disclosed in D1. The board saw only two differences between claim 1 and D1 which might support the presence of an inventive step, namely that the claimed method was used for liveness detection and that it considered also quality parameters other than those disclosed for the "specialized classifiers" of D1. For the appellant, D1 did not qualify as the closest prior art as it was concerned with authentication rather than with liveness detection.

In the board’s view, the novelty requirement provides that no patent can be granted for anything that is already known. The inventive step requirement raises the bar to a patent by also excluding matter which is obvious over what is known. That which is obvious to the skilled person cannot depend on anything that the skilled person does not know yet. In particular, what is obvious at the filing date of a patent application cannot depend on the content of that patent application. Conversely, an argument that a skilled person having regard to some piece of prior art will find something to be obvious cannot be rebutted on the basis of what the application says. In particular, the application cannot be invoked to limit the prior art under consideration or the expertise of the skilled person (their "art") on the basis of the stated "field of the invention". That essentially any piece of prior art can be considered in an inventive step analysis has been stated several times in the case law. The definite articles in the phrase "the person skilled in the art" in Art. 56 EPC are not meant to limit the relevant "arts". Any successful rebuttal of an inventive step objection must address the obviousness argument directly, without reference to the application.

It is a matter of efficiency when assessing inventive step to consider only persons skilled in arts related to the claimed invention, and, consequently, only prior art which such a person may have regard to. The board considered that a person skilled in some art may well have regard to prior art from a field which is not, in a narrow sense, their "own field". It is reasonable to assume, for instance, that persons skilled in one field will typically keep themselves informed about developments in related fields, and in this sense have regard to prior art in related fields. The board disagreed with T 646/22 and held that in principle, all problems which the skilled person would have addressed (or been asked to address) based on the prior art alone are valid ones. In the present case, the board assumed a person skilled in liveness detection methods. Such a person was, generally, interested in improving, or finding alternatives to, known liveness detection methods, based on the knowledge that known methods have known pitfalls. Liveness detection for authentication and authentication were closely related technical areas. The board noted that it was typical to try adapting developments in neighbouring fields to the own area of interest. It was certainly common practice in image processing, in particular when the images were of the same type. Thus, in the board's judgement, the person skilled in the art in liveness detection would have regard to D1 and would have reason to adapt its solution to liveness detection in a way leading to the invention according to claim 1 of the main request before the examining division. The current requests differed from that request ("quality parameter").

Finally, the board noted that during examination a relatively large number of documents were cited, some of them concerned with liveness detection, but were not discussed in the decision. A positive decision on inventive step could not be issued before at least these documents have been discussed (Remittal).