2019 edition of the EPO’s Guidelines for Examination now in force

The latest edition of the Guidelines for Examination in the European Patent Office came into force on 1 November 2019. We review the amendments to the Guidelines that are relevant to patenting inventions incorporating mathematical methods.

Inventions in all fields of technology can make use of mathematical methods to provide a technical solution to a technical problem. Examples include signal encryption/decryption, controlling a technical process, simulating a technical process and feature recognition based on an analysis of image data.

Inventions based on mathematical methods are, however, excluded from patentability under Article 52(2)(a) EPC, when claimed as such (Art. 52(3) EPC). For example, deconvolution of a first abstract signal from a second abstract signal is a mathematical method as such and so is excluded from patentability.


One approach for overcoming the subject-matter exclusion under Article 52(2)(a) EPC is to add additional technical means (e.g., a computer) to a claim so that the claim as a whole has technical character. In such cases, the claim is subsequently assessed on the basis of its technical features for novelty and inventive step, the computer in the previous example.

Developing the above approach, it may also be possible for some or all of the steps of a claimed mathematical method to have technical character so that these also enter into the assessment of novelty and inventive step. Success here usually requires the terms of a claim that relate to a mathematical method to be clear, otherwise their technical character may be in doubt. As newly stated in the 2019 EPO Guidelines, G-II, 3.3

This is of particular importance where such terms are used in significantly different ways in the application itself and/or in relevant prior art documents, as this may be an indicator that the terms have no well-recognised meaning and may leave the reader in doubt as to the meaning of the technical features to which they refer, which may lead to findings of lack of technical character of the claims.

Accordingly, a European patent application for an invention based on a mathematical method should, to maximize its prospects, contain sufficient support (e.g., a suitably detailed description) that allows its reader to understand:

  • the technical character of any step(s) of the mathematical method; and
  • how the technical characteristics of the mathematical method provides a technical solution to a technical problem, whether in isolation or in combination with any other technical features of the invention.

A subtle point here is that relying on the technical nature of data or parameters that form part of a mathematical method may not on its own be sufficient to overcome Art. 52(2)(a) and (3) EPC. This is because, unless technical means are at least implied in relation to performing the claimed mathematical method, the claimed method may instead fall into another excluded subject-matter category: methods for performing mental acts (Art. 52(2)(c) and (3) EPC). For an example of how this point is assessed in practice by the EPO, see T 0914/02 (Designing a core loading arrangement for loading nuclear reactor fuel bundles into a reactor core). 


Case law of the EPO Boards of Appeal has established that a mathematical method having higher algorithmic efficiency than prior art mathematical methods cannot rely on algorithmic efficiency for a technical effect if:

  • the mathematical method does not serve a technical purpose; and
  • the claimed technical implementation does not go beyond a generic technical implementation.

See, for example, T 1784/06 (Classification method/COMPTEL).

New to the 2019 edition of the Guidelines, the EPO’s approach to examining mathematical methods the effects of which are converse to the above has been clarified (G-II, 3.3) –

However, if it is established that the mathematical method produces a technical effect when it is applied to a field of technology and/or adapted to a specific technical implementation, the computational efficiency of the steps affecting that established technical effect is to be taken into account when assessing inventive step.

Similarly, if a further technical effect of a computer program has been established, the computational efficiency of an algorithm affecting the established technical effect contributes to the technical character of the invention and thus to inventive step (G-II, 3.6). A helpful example provided by the EPO in this context is where the design of the algorithm is motivated by technical considerations of the internal functioning of the computer on which the algorithm is run.


The 2018 edition of the Guidelines for Examination was the first to include a section directed to artificial intelligence (AI) (see here for our commentary on that update and here for our summary of AI patenting trends in the UK). In the 2019 edition, the updates to the examination of AI-based inventions are of a clarifying nature, rather than introducing extensive new guidance.

Within the AI art, the EPO Guidelines state that (G-II, 3.3.1) –

Terms such as "support vector machine", "reasoning engine" or "neural network" may, depending on the context, merely refer to abstract models or algorithms and thus do not, on their own, necessarily imply the use of a technical means. This has to be taken into account when examining whether the claimed subject-matter has a technical character as a whole (Art. 52(1), (2) and (3)).

In other words, a support vector machine claimed as such in a European patent application may not, unless the context indicates otherwise, be patent-eligible subject-matter. Without technical character, the support vector machine as such would not be assessed for novelty and inventive step.

To avoid this pitfall, the same advice as for seeking patent protection for mathematical methods applies:  the models and algorithms on which an AI invention is based should, to maximize the prospects of a patent being granted, be disclosed in a way that clearly describes: their technical character; their interaction with any other technical features comprised by the invention; and their corresponding technical effect(s). In this respect, the 2019 Guidelines for Examination maintains the 2018 guidance on inventive step assessment for claims comprising technical and non-technical features (G-VII, 5.4).


Inventions may rely on mathematical methods to realize novelty and inventiveness over the prior art.  Appreciating how EPO examiners assess patent-eligible subject-matter in this technology area is, therefore, an important early step on the path to obtaining patent protection. In this respect, the amendments to the 2019 Guidelines discussed in this IP Update provide welcome clarification on how this assessment is performed.