15 September 2023

A warning on free beers: EPO confirms “whole range sufficiency” test applies to broadly claimed mechanical inventions (T 0149/21)

This decision of the European Patent Office (EPO) Boards of Appeal clarifies that the concept of ‘whole range sufficiency’ applies to all types of inventions, not just to fields of chemistry and medical use, and highlights the potential dangers in reaching for too much in broadly claimed mechanical inventions that often encompass technically reasonable embodiments not described.

Background to whole range sufficiency

A fundamental legal requirement for a patent application is to disclose an invention in sufficient detail to enable it to be reproduced by a notional skilled person without undue burden using their common general knowledge (Article 83 EPC). According to established case law, in order to meet the requirements of Article 83 EPC, a detailed description of at least one way of carrying out the invention must be given in the application, but this is sufficient only if it allows the invention to be performed across the whole claim scope (see CLBA II-C 5.2 and 5.4).

Since the application is addressed to a skilled person armed with the common general knowledge in the field, a lot of weight is often given to the skilled person’s knowledge and ability to fill in gaps and missing details in a disclosure, and even to exclude certain embodiments falling with the scope of the claim that make no technical sense, in order to put the invention into practice and meet the requirements of Article 83 EPC (CLBA II-C 4.1). In fact, the EPO explicitly discourages the drafter from describing every little detail of an invention for this reason (see GL Part F-III 1). As such, a sufficiency objection requires there to be serious doubts, substantiated by verifiable facts, that the skilled person would be able to work the invention as claimed.

The sufficiency requirement can often be satisfied by providing a detailed description of a single working embodiment falling within the scope of the claims (which is also a formal description requirement of Rule 43(1)(e) EPC). Indeed, this is often the case for mechanical and electronic-type inventions which are typically defined by concrete structural elements with some specific function(s) that attempt to generalise the teaching in the description. But it may not be the case for certain inventions, such as chemistry and medical use inventions, that cover a broad field and range of embodiments whereby the inherent doubt that the invention can be reproduced over the claim scope is higher. For such broadly claimed inventions, the description may need to go to greater lengths in detailing a series of embodiments covering the “whole range claimed” to satisfy Article 83 EPC (see e.g. T 409/91, reasons 2; T 435/91, reasons 2.2.3; T 862/11, reasons 5.2 (b); T 941/16, reasons 9; all in the field of chemistry). This is even more the case where a claim contains a functional element defining a desired technical effect or result to be achieved, whereby the effect should be plausibly achieved over the whole claim scope to satisfy Article 83 EPC (see GL Part F-III, 12 and CLBA II-C, 6.1).

The concept of ‘whole range sufficiency’ would thus appear to be a matter of settled case law – a fundamental principle applying to any invention irrespective of the technology or how it is claimed. However, in a number of recent EPO case law decisions in the field of mechanics (see e.g. T 2773/18 reasons 3.2; T 500/20 reasons 3.6; T 1983/19 reasons 2.1.3; and T 0155/21 reasons 5.3.3), the Boards have suggested that the concept of whole range sufficiency was developed in the fields of chemistry where a central aspect of the invention usually resides in a range of compositions or other parameter values, and is not necessarily applicable to inventions in other fields such as mechanics that do not involve a range of parameter values or compositions.

In particular, the Board in T 500/20 stated (see reasons 3.6) “In claimed inventions that do not involve a range of parameter values or compositions basing an argument of insufficiency on this approach [the whole range sufficiency approach] is inappropriate and can be rejected offhand for that reason.

These decisions might therefore throw some uncertainty surrounding how sufficiency is to be assessed for different types of inventions. The question of whether the concept of whole range sufficiency should be limited to any specific technical field is specifically addressed in decision T 0149/21.

Decision T 0149/21 – summary of facts and submissions

T 0149/21 was an appeal against the decision of the Opposition Division to maintain the patent as granted (EP2630545). The patent in suit (EP2630545) relates to a method for reducing the energy consumption of a rolling mill installation and is thus firmly set in the field of mechanics. During the operation of such a plant, there are rolling breaks of the rollers of different lengths, e.g., for a roll change or in case of malfunctions. In the event of unplanned rolling breaks, the system components that are not directly affected by the rolling break (e.g., fume extraction, hydraulic systems, heating, sensors, etc.) are normally not switched off and continue to consume power. The invention is aimed at “maximizing the energy-saving potential of a rolling mill during a break in rolling” by automatically shutting down as many of the system components as possible whose shut-down and re-start time is shorter than the duration of the rolling break.

Claim 1 as granted specified a method including steps of, among other things (paraphrasing):

a. identifying a type of fault that led to an unplanned rolling break and feeding that to a control device, and

b. the control device determining the probable duration of the rolling break based on the identified type of fault.

In the decision under appeal, the Opposition Division concluded that the patent was sufficiently disclosed for a person skilled in the art to carry it out, namely because at least one way of carrying out the invention within the scope of the claims is described. Specifically, in paragraphs [0008] and [0025] of the patent in suit, an embodiment is described in which a ‘roller operator’ manually identifies the type of fault who then inputs this to a control device (c.f. step a). The control device then determines the probable duration of the rolling break (cf. step b) on the basis of a database ‘fault matrix.’

The decision

The Board in T 0149/21 disagreed with the Opposition Division. In interpreting the claims (see reasons 2.1-2.2), the Board considered the feature of step (a) to encompass both manual identification (i.e. performed by the roller operator as in paragraphs [0008] and [0025]) and automatic identification of faults. The Board further noted that claim 1 is not limited to any particular type of fault, so the fault in steps (a) and (b) can include previously known faults or unknown faults.  

The Board considered, with regards to step (a), that the patent only describes manual fault identification, and the skilled person would not be able to provide for automatic identification only on the basis of his general knowledge. With regards to step (b), in the Board’s view, the determination of a probable duration of the rolling break based on a fault matrix, as set out in paragraph [0025] of the patent in suit, can only be made for faults that are already known (see reasons 2.2). No other ways of determining the duration of the rolling break are described in the patent. Thus, it is not clear how the probable duration of faults that are previously unknown could be determined based on the information in the patent and common general knowledge.

The proprietor had argued (see reasons 3.2 and 3.5 of the decision) that, according to case law, it was sufficient that at least one way of carrying out the invention was shown in order to satisfy Article 83 EPC, and that the requirement of whole range sufficiency was not applicable to the field of mechanical inventions, citing T 2773/18, T 500/20 and T 1983/19. Whether other ‘exotic’ scenarios also fall within the scope of the claim is irrelevant in this context. The proprietor argued that the consideration of all the possible types of faults that might fall within the claim scope would lead to an excessive requirement on the enforceability of Article 83 EPC, and used examples such as a nuclear bomb exploding or an airplane crashing into the rolling mill as unknown fault types causing the rolling break.

However, the Board held that while the indication of one way of carrying out the claimed invention is sufficient to satisfy the description requirement under Rule 42(1)(e) EPC, it is not necessarily sufficient to satisfy Article 83 EPC. According to the settled case law of the Boards of Appeal, the claimed invention must be capable of being carried out over the entire claimed area (see e.g. T 409/91, reasons 2; T 435/91, reasons 2.2.3; T 862/11, reasons 5.2 (b); T 941/16, reasons 9; all in the field of chemistry), and this jurisprudence is usually not limited in any way to the respective subject area. To support this view, the Board cited a large body of case law supporting the application of ‘whole range sufficiency’ to fields outside of chemistry and medical uses, including electrical engineering (see e.g. T 1542/12, reasons 2.1.1; T 2210/16, reasons 3.2; T 1306/17, reasons 4.2), physics (see e.g. T 2305/14, reasons 3.2; T 222/17, reasons 12; T 1921/19, reasons 1.1.3), and mechanics (see e.g. T 1905/10, reasons 1.3.3; T 2431/11 reasons 4.2 and 4.10). Further, the Board noted that the requirement of whole range sufficiency is in line with fundamental legal and political concern that, in principle, the exclusive right conferred by a patent with regards to its claim scope should be limited by the actual contribution to the state of the art (see T 435/91, reasons 2.2.1).

Notably, the Board made a distinction between embodiments falling within the scope of the claims that are ‘technically reasonable’ which the skilled person would objectively understand, and those which are merely ‘theoretically possible.’ The latter, for which the nuclear bomb and plane crash scenarios put forward by the proprietor are clearly examples of, are not a technically sensible and can be ignored for the purposes of Article 83 EPC, whereas the former should be taken into account for the purposes of Article 83 EPC.

In the present case, the embodiments of automatic identification of a fault type and previously unknown fault types are, in the Boards’ view, examples of technically reasonable embodiments falling within the scope of the claims, because the skilled person would be familiar with the possibility of automatically identifying a type of fault in the context of a rolling mill through common general knowledge, and previously unknown faults (new faults) can legitimately occur (see reasons 3.7).

Consequently, the Board held (contrary to the Opposition Division’s view in reasons 4.3 of the contested decision) that claim 1 is not sufficiently disclosed across its whole scope (see reasons 3.10-3.11).


The decision in T 0149/21 clarifies that the concept of whole range sufficiency is not limited in any way to a particular technical field and emphasises that all ‘technically reasonably’ embodiments falling with the entire scope of the claims should be sufficiently disclosed to meet the requirements of Article 83 EPC. Accordingly, care should be taken when drafting applications in all fields of technology to consider all the technically feasible variants and ensure there is sufficient information in the application to put them into practice.

In particular, reaching too far with broadly claimed functional features (so-called ‘free beer’ claims) in the fields of mechanics, electronics and physics, which by design may comprise an indefinite and abstract host of possible alternatives, could be problematic if only one way of carrying out the invention is described. In such cases, a single example may suffice if the patent discloses a technical concept fit for generalisation and a generalisable teaching which makes the host of variants encompassed by the functional definition available to the skilled person (see CLBA II-C 5.4).