The exclusion from patentability of schemes, rules and methods for performing mental acts under Art. 52(2)(c) concerns instructions to the human mind on how to conduct cognitive, conceptual or intellectual processes, for instance how to learn a language. The exclusion applies only when such schemes, rules and methods are claimed as such (Art. 52(3)).
If a method claim encompasses a purely mental realisation of all method steps, it falls under the category of methods for performing mental acts as such (Art. 52(2)(c) and (3)). This applies regardless of whether the claim encompasses also technical embodiments and of whether the method is based on technical considerations (T 914/02, T 471/05, G 3/08).
An example is a claim defining a method for designing an arrangement for loading nuclear reactor fuel bundles into a reactor core in order to maximise the amount of energy that is generated before the reactor fuel needs to be refreshed. The method involves determining optimal values for specific technical parameters of the arrangement by starting with initial values, performing simulations based on these values, and iteratively changing the values based on simulation results until a stopping criterion is met. Such a method is based on technical considerations related to the technical field of nuclear reactors. However, as long as the claim does not exclude that all method steps may be carried out mentally, the claimed subject-matter is excluded from patentability. This objection also applies when the simulation involves real world values obtained by a technical measurement, if the claim does not include the step of carrying out the technical measurement.
In general, the complexity of a method cannot disqualify it as a method for performing mental acts as such. If technical means (e.g. a computer) are necessary to carry out the method, they are included in the claim as an essential feature (Art. 84, F‑IV, 4.5). See also G‑II, 3.3 for aspects related to algorithmic efficiency.
A claimed method is not a method for performing mental acts as such if it requires the use of technical means (e.g. a computer, a measuring device, etc.) to carry out at least one of its steps or if it provides a physical entity as the resulting product (e.g. if it is a method of manufacturing a product comprising steps of designing the product and a step of manufacturing the product so designed).
Once it is established that the claimed method as a whole is not excluded from patentability under Art. 52(2) and (3), it is examined in respect of the other requirements of patentability, in particular novelty and inventive step (G‑I, 1).
Where a claim defining a method for performing mental acts as such is limited by specifying that the method is carried out by a computer, not only the use of a computer but also the steps carried out by the computer themselves may make a technical contribution if they are based on technical considerations and serve a technical purpose. This would be the case with the aforementioned method for designing a core loading arrangement if it were automated (see also G‑II, 3.3.2).
A method comprising steps which involve the use of technical means may also specify steps which are to be carried out mentally by the user of the method. These mental steps contribute to the technical character of the method only if, in the context of the invention, they contribute to producing a technical effect serving a technical purpose.
For example, a method may specify steps which result in the selection of a product among a family of products based on various criteria, as well as a step of manufacturing the selected product. If said selection steps are carried out mentally, they contribute to the technical character of the method only to the extent that a technical effect can be derived from the features characterising the sub-family of selected products over the generic family of suitable products (T 619/02). If the selection steps rely on purely aesthetic criteria, they result in a non-technical selection and thus do not contribute to the technical character of the method. As another example, in a method of affixing a driver to a Coriolis mass flowmeter, steps specifying how to select the position of the driver so as to maximise the performance of the flowmeter make a technical contribution to the extent that they define that particular position (T 1063/05).